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Lithogenic Risk Factors in the Morbidly Obese Population
Abstract
To our knowledge baseline lithogenic risk factors in the morbidly obese population are currently unknown. Prior studies evaluated known stone formers and correlated risk with increasing body mass index. We describe risk factors for urinary stone formation in a group of unselected morbidly obese patients.
Patients scheduled for gastric bypass provided a 24-hour urine collection before surgery. Patient demographics, medications and supplement consumption were recorded. A dietary intake diary was converted into daily kcal, Ca, Na and protein consumption. Differences between groups based on gender, history of diabetes or nephrolithiasis, diuretic use and Ca supplementation were evaluated. Correlation of stone risk parameters with body mass index was evaluated.
A total of 45 patients provided samples for analysis. Mean +/- SD body mass index was 49.5 +/- 9.1 kg/m(2) and mean age was 47.0 +/- 10.5 years. Overall 97.8% of patients had at least 1 lithogenic risk factor identified. Low urinary volume was the most common abnormality, affecting 71.1% of patients. Male patients excreted significantly more Ox (p = 0.0014), Na (p = 0.020), PO(4) (p = 0.0083) and SO(4) (p = 0.0014) than females. Patients with a history of nephrolithiasis excreted significantly more oxalate (p = 0.018) and had higher relative Na urate supersaturation (p = 0.00093) than nonstone formers. Hydrochlorothiazide use was associated with significantly increased Na urate relative supersaturation (p = 0.0097). Increasing body mass index was inversely associated with Mg (r = -0.38, p = 0.01) and brushite (r = -0.30, p = 0.04).
Of our cohort of morbidly obese patients 98% had at least 1 lithogenic risk factor identified on 24-hour urine collection. This study identified a high urinary stone risk in the morbidly obese and suggests possible avenues for dietary and/or pharmacological preventive measures. Future studies will determine how bariatric surgery alters these risk factors.
... The risk of stone disease in obesity is inversely associated with urinary pH, and such an acidic urinary environment is a notable risk factor for both uric acid and calcium oxalate stones (Maalouf et al., 2004;Cameron et al., 2006). However, the literature base, to-date, is equivocal as to the association between body mass index and stone formation (Siener et al., 2004;Powell et al., 2000;Ekeruo et al., 2004;Taylor and Curhan, 2006;Duffey et al., 2008), highlighting the need for a meta-analytical assessment, to provide empirical, consensual. Thus, the aim of the present study was to evaluate the impact of body mass index on urinary excretion of different metabolites in patients with nephrolithiasis. ...
... The crystallization is influenced by various factors, including a lack of crystallization inhibitors (such as citrate and magnesium), the presence of crystallization promoters (for example calcium, oxalate and uric acid), and some morpho-anatomic characteristics (Muñoz et al., 2012). Regarding the level of 24-h urine metabolites in obese stone formers, it was previously demonstrated that the urinary excretion of sodium, calcium, uric acid, oxalate, phosphate and ammonium is higher in obese stone formers compared to normal weight patients (Powell et al., 2000;Duffey et al., 2008). Concordantly, our results indicated that the level of 24-h urine sodium, calcium, uric acid, oxalate, phosphate, urea and creatinine was higher in overweight and obese stone forming patients. ...
... In the present study, we observed that the level of 24-h urinary magnesium and citrate was higher in obese patients; while 24-h urine volume was also significantly greater in BMI≥25 kg/m 2 group. The findings of previous studies for urinary excretion of citrate, magnesium and 24-h volume are contradictory; indeed, some studies have suggested no difference for these parameters between obese and normal weight patients, whereas many others have proposed an increase of these parameters in obese patients (Powell et al., 2000;Taylor and Curhan, 2006;Duffey et al., 2008;Wang et al., 2018;Murphy et al., 2018;Bandari et al., 2016). Although the increases in urinary metabolites might simply be explained by the greater volume, some studies have suggested that urine osmolality is also higher in obese patients, which results in more concentrated urine (Powell et al., 2000). ...
Objective
The aim of the present study was to evaluate the impact of body mass index (BMI) on urinary excretion of different metabolites in patients with nephrolithiasis.
Methods
A systematic search of PubMed and Scopus was performed up to July 2019. The eligible studies based on inclusion/exclusion criteria were screened and their data were extracted. Finally, 91 articles were included for dose response analysis, of which, 14 articles were included. Patients were dichotomized according to their BMI, i.e. normal weight patients with BMI˂25 and overweight/obese patients with BMI≥25 kg/m².
Results
Our results indicated that normal weight stone forming patients excreted less calcium (p<0.001), uric acid (p<0.001), oxalate (p<0.001), sodium p<0.001), citrate (p<0.001) and magnesium (p<0.001), however, these patients also had a higher urinary pH (p<0.001). There was a linear dose-response relationship between BMI and 24-h excretion of oxalate (p linearity˂0.001), uric acid (p linearity ˂ 0.001), sodium (p linearity= 0.002), phosphate (p linearity = 0.006), citrate (p linearity = 0.003) and creatinine (p linearity=0.0006), respectively.
Conclusion
The findings from the present study highlight overweight and obesity increase the urinary excretion of both stone promoters (calcium, sodium, oxalate and uric acid) and inhibitors (citrate and magnesium) urinary pH and prevalence of kidney stones is still higher in overweight/obese patients. Overall, overweight and obese people have more chance to form the kidney stones.
... Kidney stones were previously thought to be uncommon in children and adolescents but in the younger age group the incidence appears to also be increasing [1,2]. Previous observational studies in obese adults have shown abnormal urinary metabolic indices that predispose to crystal aggregation and calculus formation [3,4]. In addition, gastric bypass procedures have been implicated in the development of enteric hyperoxaluria [5]. ...
... Several urinary metabolic studies have been performed in obese adults to assess lithogenic risk factors. Duffey et al studied 45 subjects with a mean BMI of 50 kg/m 2 and found that 98% had at least one risk factor, mainly low urinary volume [3]. Taylor and Curhan reported that subjects with greater BMI values excreted more urinary oxalate, uric acid, sodium, and phosphate than those with lower BMI. ...
... However, it is concerning that a majority of patients did have at least one abnormal urinary risk factor. None of these were isolated low urine volume as reported by Duffey [3]. ...
Observational studies in obese adults have found abnormal urinary metabolic indices that predispose to nephrolithiasis. Few studies have been performed in severely obese adolescents.
To assess urinary stone risk factors in severely obese adolescents and in those undergoing 2 types of weight loss surgery.
Children's hospital, United States.
A prospective cross-sectional study was performed to assess urinary metabolic profiles in severely obese adolescents who either have not undergone any gastrointestinal surgery or who have undergone Roux-en-Y gastric bypass (RYGB) or vertical sleeve gastrectomy (SG). Twenty-four-hour urine collections were performed at home and evaluated at a central laboratory. Established normal reference ranges for adults were used in the analysis. A linear regression analysis was performed assessing the relationship of the study group with each of the outcomes.
A total of 55 samples were analyzed from 14 severely obese adolescents and from 17 severely obese adolescents after bariatric surgery (RYGB, 10; SG, 7). Median body mass index was similar between the RYGB and SG groups. The median 24-hour excretion of oxalate was significantly elevated in the RYGB group. Calcium and uric acid excretion and the median supersaturation of calcium oxalate, calcium phosphate, and uric acid were similar among all groups.
Elevated excretion of oxalate in the urine of severely obese adolescents and in those who have undergone RYGB may portend increased risk for kidney stone formation. Larger longitudinal studies are needed to verify these findings and to determine the clinical risk of developing stone disease in these patient populations.
Copyright © 2015 American Society for Metabolic and Bariatric Surgery. Published by Elsevier Inc. All rights reserved.
... Современные эпидемиологические данные свидетельствуют о существенном росте заболеваемости уролитиазом в общей популяции [67][68][69][70]. Эта общемировая тенденция идет параллельно с ростом частоты ожирения и МС как у мужчин, так и у женщин, что является неоспоримым доказательством патогенетического единства уролитиаза и МС [67,68]. ...
... Современные эпидемиологические данные свидетельствуют о существенном росте заболеваемости уролитиазом в общей популяции [67][68][69][70]. Эта общемировая тенденция идет параллельно с ростом частоты ожирения и МС как у мужчин, так и у женщин, что является неоспоримым доказательством патогенетического единства уролитиаза и МС [67,68]. Наибольшее практическое значение имеет факт высокой частоты встречаемости уролитиаза у лиц среднего, самого трудоспособного возраста (20-55 лет), что обусловливает определенные финансовые потери общества в связи с временной утратой трудоспособности по поводу лечения различных клинических вариантов мочекаменной болезни [69]. ...
Current review provides a multifaceted analysis of epidemiological, clinical and experimental evidence for insulin resistance as a systemic player in the development of renal pathology. We discuss both established and potential mechanisms for this effect. Aside from being a marker for glycemic disorders, insulin resistance was shown to be an independent predictor of renal pathology, including such chronic conditions as urolithiasis, renal cysts and malignant renal neoplasms. Early detection and correction of insulin resistance is a promising approach to diagnostics, treatment and prevention of renal pathology.
... Obese people account for more than 300 million people in the Western world. It is universally acknowledged that being overweight poses a significantly higher risk of urinary stone formation because of increased urinary excretion of uric acid, oxalate, and calcium [68][69][70]. as a consequence, an ever-growing number of obese patients will present to our departments because of urolithiasis, challenging urologists all over the world. Obese patients may represent a real challenge because they usually have several comorbidities, with metabolic syndrome (hypertension, obesity, diabetes, and abnormal lipid levels) being the most common scenario affecting such patients. ...
... Obese patients may represent a real challenge because they usually have several comorbidities, with metabolic syndrome (hypertension, obesity, diabetes, and abnormal lipid levels) being the most common scenario affecting such patients. Unfortunately, SWL does not represent a viable treatment option because it has been demonstrated that its effectiveness is significantly compromised when the distance from the skin to the stone is more than 10 cm, as usually happens for those with body mass index higher than 30 [70]. For obese patients, anesthesia could represent a major concern because intubation and high-pressure ventilation may be necessary during surgery [71]. ...
Purpose:
To critically review and synthesize data of ureteroscopy (URS) in different circumstances that all urologists may encounter during everyday clinical practice, such as pregnancy, obesity, bleeding diathesis, renal stones larger than 2 cm, calyceal diverticula, and kidney malformations.
Methods:
According to PRISMA guidelines, a systematic literature review was performed to identify articles published between 1990 and December 2013 that reported different indications and special circumstances for URS. Articles were separated into the following categories: pregnancy, obesity, bleeding diathesis, stones larger than 2 cm in diameter, calyceal diverticula, and kidney malformations. We used a narrative synthesis for the analyses of the studies, including a description of the characteristics and main outcomes reported in the articles.
Results:
Records identified through database searching were 1396; at the end of study selection, articles included were 57. The majority of these are retrospective studies and involve small cohorts of patients. There does not exist a consensus about important parameters in ureterorenoscopy like stone size, stone free status and complication rate.
Conclusion:
Ureteroscopy is effective and reliable tool capable of treating the majority of stones even in the most complicated clinical scenarios and will have more fundamental roles in endourology. The lack of definitive conclusions is due to the great heterogeneity in collecting study's results; multicentric randomized trials that define in advance the parameters to be studied should be encouraged.
... Past studies have examined the impact of body size on urine chemistry, revealing that an increase in BMI may potentially elevate lithogenic risk factors. These factors involve reducing urinary volume and citrate concentrations (52). Another study indicated that middle-aged, hypertensive white males might serve as an indicator for nephrolithiasis, which is characterized by the development of kidney stones and has been linked to increased and prolonged urinary calcium excretion in hypertensive patients (53). ...
Aims
The primary objective of this study was to investigate the relationship between the platelet/high-density lipoprotein cholesterol ratio (PHR) and the prevalence of nephrolithiasis within the adult population of the United States.
Methods
The data used in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2018. The analysis included a non-pregnant population aged 20 years or older, providing proper PHR index and nephrolithiasis data. The research utilized subgroup analyses and weighted univariate and multivariable logistic regression to evaluate the independent association between the PHR and the susceptibility to nephrolithiasis.
Results
The study comprised 30,899 participants with an average PHR value of 19.30 ± 0.11. The overall prevalence rate of nephrolithiasis was estimated at 9.98% with an increase in the higher PHR tertiles (T1, 8.49%; T2, 10.11%; T3, 11.38%, P < 0.0001). An elevated PHR level was closely linked with a higher susceptibility to nephrolithiasis. Compared with patients in T1, and after adjusting for potential confounders in model 2, the corresponding odds ratio for nephrolithiasis in T3 was 1.48 (95% CI: 1.06 to 2.08), with a P-value = 0.02. The results of the interaction tests revealed a significant impact of chronic kidney disease on the relationship between PHR and nephrolithiasis. Furthermore, the restricted cubic spline analyses exhibited a positive, non-linear correlation between PHR and the risk of nephrolithiasis.
Conclusion
A convenient biomarker, the PHR, was independently associated with nephrolithiasis and could be a novel biomarker in predicting occurrence in clinical decision.
... In addition, many studies have reported that metabolic syndrome, including obesity, hypertension, dyslipidemia, and hyperglycemia, increases the risk of nephrolithiasis [22][23][24][25]. Not only is body size positively associated with daily oxalate excretion [26], but obesity is also related to low urinary pH (potential of hydrogen), which may increase the risk of uric acid stone formation [27]. ...
Workers in high-temperature workplaces with inadequate water supply may exhibit symptoms of chronic dehydration and have increased risk of nephrolithiasis. The aim of this study was to investigate the risk of radiolucent stone formation among workers in a high-temperature workplace and the related risk factors associated with the condition. We collected data from 1681 workers in a steel factory in Southern Taiwan who underwent regular health examinations. Radiolucent stones were defined as positive findings on ultrasound with negative radiographic images. The prevalences of nephrolithiasis and radiolucent stones in this study were 12.0% and 5.1%, respectively. Heat exposure and age were two major risk factors influencing the probability of radiolucent stones. We combined the age and heat exposure into four groups (over and under 35 years of age with and without heat exposure) in a logistic regression. For workers younger than 35 years, the odds ratio of radiolucent stones was 2.695 (95% confidence interval: 1.201–6.049) in workers with heat exposure compared to workers without. Our investigation further demonstrated that heat exposure was a main risk factor for radiolucent stone formation. In conclusion, our identification of heat exposure as an independent factor for radiolucent stone development in steel workers highlights the need for attention to be paid to those working in similar environments.
... Semins et al. (32) found that the obese population had a higher risk of kidney stone, while as the degree of obesity stratified by BMI increased, the risk stabilized. Previous studies exploring the effect of body size on urine chemistry demonstrated that increasing BMI could enhance the lithogenic risk factors such as decreased urinary volume and citrate concentrations (33). Chronic inflammation in adipose tissue was considered to be a key risk factor for IR and type 2 diabetes in obese individuals. ...
Aims
We aimed to assess the association between triglyceride–glucose (TyG) index and kidney stones in US adults.
Methods
Data were obtained from the 2007–2014 National Health and Nutrition Examination Survey (NHANES). Participants aged ≥18 years who were not pregnant and provided complete data about TyG index and kidney stones were included in the analysis. Weighted multivariable regression analysis and subgroup analysis were preformed to estimate the independent relationship between TyG index and nephrolithiasis and recurrence.
Results
A total of 20,972 participants were included with the mean TyG index of 8.71 ± 0.72. The prevalence rates of nephrolithiasis and recurrence were 9.30% and 3.17% overall and increased with the higher TyG index tertiles (Nephrolithiasis: Tertile 1, 6.98%; Tertile 2, 9.15%; Tertile 3, 11.98%, p < 0.01; Recurrence: Tertile 1, 1.84%; Tertile 2, 3.27%; Tertile 3, 4.50%, p < 0.01). Each unit increase in TyG index was associated with 12% and 26% higher odds of nephrolithiasis [odds ratio (OR) = 1.12; 95% CI: 1.02–1.22; p = 0.02] and recurrence (OR = 1.26; 95% CI: 1.08–1.46; p < 0.01). Interaction tests indicated no significant effect of gender, age, body mass index, hypertension, and diabetes on this association between TyG index and kidney stones.
Conclusions
Higher TyG index was associated with an increased likelihood of nephrolithiasis and recurrence. Considering TyG index is a reliable indicator of insulin resistance (IR). Treatment and management of IR at a younger age may improve or alleviate the occurrence and recurrence of kidney stones.
... Brolin et al. [28] VBG or RYGB To assess dietary intakes, 38 studies used FR [16,[19][20][21]24,27,31,36,39,[41][42][43]46,[51][52][53][57][58][59][61][62][63]68,70,72,74,80,81,91,94,99,100,105,107,111,112,118,121], 32 used 24HR [23,25,32,35,37,44,45,49,60,64,67,73,[77][78][79][85][86][87][88][89][90]92,[95][96][97][98]106,110,115,119,122,123], 16 used FFQ [18,26,40,48,50,65,76,84,[101][102][103][104]108,109,114,117], 8 used questionnaires (6 were inspired by FFQ [29,66,69,71,93,120] and 2 did not provide details [22,55]), 2 used other dietary assessment methods (photo-assisted capture method and food and symptom diary) [17,75], and 12 studies used combined tools [28,30,33,34,38,47,54,56,82,83,113,116] (Table 2). Among all studies included, 27 used a dietary assessment tool that had been validated either as part of the study per se (n = 11) or in a previous study (n = 16) (Figure 2). ...
Severe obesity is associated with major health issues and bariatric surgery is still the only treatment to offer significant and durable weight loss. Assessment of dietary intakes is an important component of the bariatric surgery process.
Objective:
To document the dietary assessment tools that have been used with patients targeted for bariatric surgery and patients who had bariatric surgery and explore the extent to which these tools have been validated.
Methods:
A literature search was conducted to identify studies that used a dietary assessment tool with patients targeted for bariatric surgery or who had bariatric surgery.
Results:
108 studies were included. Among all studies included, 27 used a dietary assessment tool that had been validated either as part of the study per se (n = 11) or in a previous study (n = 16). Every tool validated per se in the cited studies was validated among a bariatric population, while none of the tools validated in previous studies were validated in this population.
Conclusion:
Few studies in bariatric populations used a dietary assessment tool that had been validated in this population. Additional studies are needed to develop valid and robust dietary assessment tools to improve the quality of nutritional studies among bariatric patients.
... Morbid obesity or type III obesity has a different impact on health than moderate obesity by increasing the risk and severity of many cardiovascular and non-cardiovascular comorbidities. Particularly, it was observed that 98% of subjects with morbid obesity have at least one lithogenic risk factor identified on 24-hour urine collection (7). The obese population of the United States is therefore a different popula-tion from obese populations observed in other countries in that it includes a higher percentage of morbid obese subjects. ...
Objective: To collect evidence on the rate of
obesity in renal stone formers (RSFs) living
in different climatic areas and consuming different diets.
Materials and methods: Data of adult renal stone formers were
retrospectively collected by members of U-merge from 13
participant centers in Argentina, Brazil, Bulgaria (2), China,
India, Iraq (2), Italy (2), Nigeria, Pakistan and Poland.
The following data were collected: age, gender, weight, height,
stone analysis and procedure of stone removal.
Results: In total, 1689 renal stone formers (1032 males, 657
females) from 10 countries were considered. Average age was
48 (±14) years, male to female ratio was 1.57 (M/F 1032/657),
the average body mass index (BMI) was 26.5
(±4.8) kg/m2. The obesity rates of RSFs in different countries
were significantly different from each other. The highest rates
were observed in Pakistan (50%), Iraq (32%), and Brazil
(32%), while the lowest rates were observed in China (2%),
Nigeria (3%) and Italy (10%). Intermediate rates were
observed in Argentina (17%), Bulgaria (17%), India (15%) and
Poland (22%). The age-adjusted obesity rate of RSFs was high�er than the age-adjusted obesity rate in the general population
in Brazil, India, and Pakistan, whereas it was lower in
Argentina, Bulgaria, China, Italy, and Nigeria, and similar in
Iraq and Poland.
Conclusions: The age-adjusted obesity rate of RSFs was not
higher than the age-adjusted obesity rate of the general popu�lation in most countries. The relationship between obesity and
the risk of kidney stone formation should be reconsidered by
further studies carried out in different populations.
... If the latter does not solve this problem, a formal cut-down may be needed to extract and reposition the sheath. 10,39 Nephrostomy tube dislodgement can also occur is obese patients. 32 can be extrapolated to robotic stone surgery in obese patients. ...
... If the latter does not solve this problem, a formal cut-down may be needed to extract and reposition the sheath. 10,39 Nephrostomy tube dislodgement can also occur is obese patients. 32 Certain measures can can be extrapolated to robotic stone surgery in obese patients. ...
Obesity is a chronic disease that has increased in prevalence in the United States and is a risk factor for the development of nephrolithiasis. As with other medical conditions, obesity should be considered when optimizing surgical management and choosing kidney stone procedures for patients. In this review, we outline the various procedures available for treating stone disease and discuss any discrepancies in outcomes or complications for the obese cohort.
... [7,[16][17][18] Furthermore, obese patients are at higher risk than nonobese patients of gouty diathesis, which may further promote the formation of uric acid stones. [14,19] The high concentration of uric acid may lead to a decrease in the solubility of calcium oxalate, which might be associated with the reduced inhibitory activity of glycosaminoglycans on the crystallization of calcium oxalates, eventually resulting in the formation of calcium oxalate stones. [20] Cystine stones generally account for 1%-2% of all kidney stones. ...
Objectives: Urinary tract stones are a common public health problem worldwide. In addition, identifying the composition of stones is important for the further metabolic evaluation of patients. We conducted this study to further correlate the relationship between body mass index (BMI) and different compositions of urinary tract stones.
Materials and Methods: A retrospective study of 433 patients who underwent urinary tract stone analysis via Fourier-transform infrared spectroscopy at King Khalid University Hospital in Riyadh from May 2015 to June 2017 was performed. Their BMI at the time of stone analysis was recorded.
Results: A total of 433 stones were analyzed by the statistical data analysis software. The BMI was classified according to the WHO classification. We divided our patients into seven age groups. Most patients were between the age group of 35 and 44 years and were overweight. The incidence of calcium oxalate, carbonate apatite, and uric acid stones was higher in patients with a BMI above thirty than in patients with a lower BMI. However, cystine stones were more common in normal-weight patients.
Conclusions: In this study, we found that the incidence of certain types of stones, such as calcium oxalate, cystine, and uric acid stones, in Saudi Arabia can be predicted by BMI measurement.
... This is comparable with findings by Negri and colleagues, 8 suggesting a different etiology, or level of BMI, in men and women to have a lithogenic influence. A different etiology is also supported by Duffey and colleagues 15 showing different excretion profiles in men and women. ...
Introduction:
Although ureteroscopy (URS) has been established as a viable treatment for stones in obese patients, its safety and success has not been fully elucidated. The current study describes the worldwide prevalence of obesity in patients with urolithiasis and examines trends in URS outcomes, safety, and efficacy.
Methods:
This study utilized the Clinical Research Office of the Endourological Society (CROES) URS Global Study, which was a prospective, multicenter study including 11,885 patients treated with URS for urinary stones at 1 of 114 urology departments across 32 countries. The relationship between body mass index (BMI), diabetes, and creatinine, with retreatment, stone-free rates, complications, and long hospital stay, was examined with a multivariate logistic regression analyses.
Results:
Of the 10,099 URS patients with BMI data, 17.4% were obese and 2.2% were super obese. Overall, 86.7% patients were stone free and 16.8% required retreatment. Higher BMI was associated with lower stone-free rates, and any deviation from normal weight was associated with higher retreatment rates. In multivariate analysis controlling for several variables including stone size, the association between BMI and lower stone-free rates with higher retreatment rates persisted. Intraoperative complications occurred in 518 (5.1%) patients, and 343 (3.4%) experienced a postoperative complication. Postoperative complications were more frequent in the underweight and super obese subjects, and there was no relationship between BMI and intraoperative complications.
Discussion:
Although URS for stone disease was found to be an overall safe procedure for obese and super obese patients, efficacy of the procedure may be lower compared with normal-weight subjects and higher retreatment rates may be necessary.
... The etiology of urinary stone disease is multi factorial and not completely well understood (Jeong et al, 2011). Recent studies have shown that obesity is associated with unique changes in serum and urinary chemistry such as increased urinary excretion of calcium, citrate, sulfate, phosphate, oxalate, uric acid and cystine contribute in stone Duffey et al, 2008; Negri et al, 2008; Asplin, 2009; Eisner et al, 2010). Some of the predisposing factors for formation of urinary stones are high concentrations of urine, deprivation of water for long time and urinary retention. ...
Urolithiasis is an important disease of food animals and a few cases are reported in camels. Camel is an
animal which anatomically and physiologically adapted itself to weather condition of desert and it can produce
urine twice more than viscosity of sea water. This investigation was undertaken to study prevalence of urolithiasis
and determination of calculi composition in camel in Najaf-Abad slaughter house, Iran. Therefore, total, 600 urinary
bladders of camel were studied. This survey showed 4 urinary stones in four 5-7 years old male camels. The frst stone
was cream, 0.5-0.7 millimeter diameter, 0.35 gram weight, rough and uneven with Calcium carbonate, ammonium
carbonate and Calcium phosphate. The second stone was cream, 0.8-0.9 millimeter, 0.65 gram, smooth with Calcium
carbonate, Calcium hydrogen phosphate, Magnesium ammonium phosphate plus other ingredients. The third stone
was cream, 0.2-0.3 millimeter, 0.15 gram with rough and uneven surface. Chemical ingredients were similar to frst
one. The fourth stone was cream, 0.2-0.5 millimeter, 0.25 gram with rough and uneven surface. Chemical ingredients
were similar to frst one. Urinary stones might be known as calcite (Calcium carbonate) and the prevalence of disease
was 0.66%. There was signifcant correlation between sex and age group with the prevalence of urinary bladder stone.
... 5 Study by Duffey et al showed 80% of the morbidly obese patients had 3 or more lithogenic factors. 6 changes in the biochemical composition of urine including phosphate, oxalate, uric acid and citrate and more acidic urine favouring stone formation. [7][8][9] Increased BMI not only contributes to the increased prevalence of urinary stones but is also associated with larger stone size. ...
... Various lithogenic risk factors, including increased body mass index (BMI), low urinary volume, hypercalciuria, hyperoxaluria and hyperinsulinemia, are associated with obesity [7] . A recent trial found that 98% of obese patients had at least one lithogenic risk factor in a-24 h urine sample and 80% had 3 or more factors [8] . As the possible biochemical mechanisms related with obesity and urinary stone disease are clearly identified, management will potentially be more effective. ...
The prevalence of urolithiasis is increasing in parallel with the escalating rate of obesity worldwide. It has previously been speculated that obesity is a potential risk factor for urinary stone disease. The possibility that common biochemical mechanisms underlie both obesity and urolithiasis is remarkable. Better understanding of possible common mechanisms of these diseases could potentially lead to a better management of urinary stone prevention. The prevention of urinary stone formation gives clinicians an acceptable reason to encourage lifestyle modification and weight loss through a regular diet. In this review, the association of obesity with urinary stone disease, possible common biochemical mechanisms, effects of dietary habits and weight loss on stone formation, as well as difficulties in surgical management of obese individuals with urolithiasis are discussed.
... Moreover, the excretion of oxalate has been linked to body weight, body surface area and to lean mass [8]. The excretion of oxalate, uric acid, sodium, phosphate and calcium rises when BMI increases [9-11]; however, the calcium excretion loses significance after correction for sodium and phosphate [9]. ...
The role of body composition (lean mass and fat mass) on urine chemistries and bone quality is still debated. Our aim was therefore to determine the effect of lean mass and fat mass on urine composition and bone mineral density (BMD) in a cohort of healthy females.Materials and methods: 78 female volunteers (mean age 46 +/- 6 years) were enrolled at the Stone Clinic of Parma University Hospital and subdued to 24-hour urine collection for lithogenic risk profile, DEXA, and 3-day dietary diary. We defined two mathematical indexes derived from body composition measurement (index of lean mass-ILM, and index of fat mass-IFM) and the cohort was split using the median value of each index, obtaining groups differing only for lean or fat mass. We then analyzed differences in urine composition, dietary intakes and BMD.
The women with high values of ILM had significantly higher excretion of creatinine (991 +/- 194vs1138 +/- 191 mg/day, p = 0.001), potassium (47 +/- 13vs60 +/- 18 mEq/day, p < 0.001), phosphorus (520 +/- 174vs665 +/- 186 mg/day, p < 0.001), magnesium (66 +/- 20 vs 85 +/- 26 mg/day, p < 0.001), citrate (620 +/- 178vs807 +/- 323 mg/day, p = 0.002) and oxalate (21 +/- 7vs27 +/- 11 mg/day, p = 0.015) and a significantly better BMD values in limbs than other women with low values of ILM. The women with high values of IFM had similar urine composition to other women with low values of IFM, but significantly better BMD in axial sites. No differences in dietary habits were found in both analyses.
Lean mass seems to significantly influence urine composition both in terms of lithogenesis promoters and inhibitors, while fat mass does not. Lean mass influences bone quality only in limb skeleton, while fat mass influences bone quality only in axial sites.
Flexible ureteroscopy is the cornerstone of diagnosis and treatment of multiple upper urinary tract pathologies, including intrarenal and ureteric stones and renal pelvic tumors. Retrograde ureteral and intrarenal surgery requires excellent knowledge of the surgical equipment, familiarization with the collecting system anatomy, and advanced endoscopic skills. However, the optimal surgical strategy lies in the hands of the operating urologist. The clinical dilemma of pre- and postoperative stenting is quite common in clinical practice and remains a matter of debate.In most instances, the surgeon must balance the obvious benefits of stenting against well-known and significant stent-related side effects such as infection, stent-related lower urinary tract symptoms, pain, and discomfort for the patient.Pre-stenting has benefits, but it may not always be possible due to clinical or other limitations, e.g., cost or availability. However, it can facilitate the operating steps, reduce surgical time, and increase the chances for a successful outcome. Similarly, postoperative stenting is not considered to be mandatory, but it is strongly recommended in complicated cases, although there is a lack of consensus of what constitutes a complicated ureteroscopy. There is a definitive agreement though on mandatory stenting in cases of any kind of ureteric violation or injury.KeywordsFlexible ureteroscopyDouble J stentUreteral sheath
In the last two decades, the share of flexible ureteroscopy (fURS) in the treatment of stone disease has increased dramatically, while the share of total treatments for percutaneous nephrolithotomy (PCNL) remained static and the share for extracorporeal shockwave lithotripsy and open surgery fell (Geraghty et al. J Endourol, 31(6):547–556, 2017). This is the result of substantial improvements in equipment, whether it be the endoscopes or laser technologies. Accordingly, the indications for the performance of fURS have increased considerably, and it has become the first-line modality in cases where it was previously impossible to perform, such as urinary diversions or anomalous kidneys.
To investigate how the risk factors of metabolic diseases affect urinary stone composition, particularly uric acid (UA) stones.
Overall, 583 patients with data on urinary stone composition were retrospectively analyzed and classified into UA and nonUA stone formers according to the presence of the UA component. Various factors were compared between both groups. Participants were categorized according to age, glucose level, HbA1c level, and estimated glomerular filtration rate (eGFR) into subgroups, and the incidence of UA stone was compared.
Overall, 137 UA stone formers (23.5%) and 446 nonUA stone formers (76.5%) were included. Mean age and male-to-female ratio were higher in the UA group than in the nonUA group. The rates of diabetes mellitus (DM), hypertension, chronic kidney disease, and coronary artery disease, all of which were associated with differences in urinary stone composition, were higher in the UA group than in the nonUA group. The UA group exhibited lower mean eGFR and higher glucose and HbA1c levels. Similarly, the UA group had higher mean UA levels and predictably lower urinary pH. In subgroup analysis, higher age, glucose level, HbA1c level, and lower eGFR were associated with an increased risk of UA stone formation. In the multivariate logistic regression analysis, the UA group showed a significantly higher age ( P < .001), DM frequency ( P = .049), and HbA1c level ( P = .032), but significantly lower eGFR than the nonUA group ( P < .001).
Age and DM were independent risk factors for UA urolithiasis, implying a relationship between urinary stone composition and metabolic diseases. Additionally, renal function and HbA1c level were risk factors for UA stones.
Objective:
The aim of the study was to assess whether severely obese patients have an increased risk of complications during and after retrograde intrarenal surgery.
Materials and methods:
The data of 639 consecutive patients undergoing retrograde intrarenal surgery for the treatment of upper tract urinary stones were analyzed retrospectively. The patients were divided into two groups according to their body mass index numbers (Group 1, <35; Group 2, ≥35). The patients' demographics, stone characteristics, operative outcomes, and complication rates were compared between the groups. The primary objective was to examine whether the intraoperative and postoperative complication rates were higher in patients with a body mass index of ≥35 kg/m2.
Results:
After matching of confounding factors, Group 1 comprised 135 patients, and Group 2 comprised 47 patients. The baseline characteristics were similar between the groups. There were no significant differences between groups for intraoperative complication rates (11.8% and 12.8%, respectively; p=0.97). There was statistically significant difference in favor of Group 2 for postoperative complication rates (12.6% and 29.7%; respectively, p<0.01), overall complication rates (22.9% and 38.2%; respectively, p=0.02), mean operation time (56.15 minute vs 66.45 minute; respectively, p= 0.01) and length of stay (1.4 days vs 2.1 days; p=0.03). Stone free rates (75.5% vs 85.1%; respectively, p=0.17) did not differ between groups.
Conclusions:
Retrograde intrarenal surgery is an efficient and feasible treatment option for upper urinary tract stones in severe obese patients. However, higher possibility of postoperative, especially infectious, complication rates should be taken into account in these patients.
Objective
The objective of the study was to estimate the dose–response relationship between body mass index (BMI) and the self-reported prevalence of kidney stones based on a restricted cubic spline (RCS) method.
Methods
This cross-sectional study analyzed 13,223 adults aged ≥20 years who had participated in the National Health and Nutrition Examination Survey performed during 2011–2016. Kidney stones were identified using a standard questionnaire, and physical examinations were used to determine BMI. Logistic regression was used to assess the relationship between BMI and the prevalence of kidney stones, with the dose–response relationship explored using RCSs.
Results
The overall prevalence of kidney stones was 9.7%: 10.6% in males and 8.9% in females. After adjusting for potential confounders, compared with those with a BMI in quartile 1, the odds ratios of kidney stones among those with BMIs in quartiles 2, 3, and 4 were 1.45, 1.60, and 2.00, respectively (95% confidence interval = 1.21–1.75, 1.33–1.92, and 1.67–2.39; all P < .001). Multivariate RCS regression revealed that BMI was related to kidney stones in a nonlinear manner (P for nonlinearity <0.001). There was a significant positive relationship, with the curves being steeper when BMI was <28 kg/m².
Conclusion
This analysis of National Health and Nutrition Examination Survey data has demonstrated that BMI is significantly associated with the prevalence of kidney stones.
Background:
Obesity has been associated with daytime urinary incontinence (UI), likely due to increased intra-abdominal pressure.
Objectives:
To assess incontinence symptoms in severely obese adolescents before and 3 years after bariatric surgery.
Setting:
Tertiary care pediatric hospitals in the United States.
Methods:
The Teen-Longitudinal Assessment of Bariatric Surgery is a prospective, multicenter study designed to evaluate efficacy and safety of bariatric surgery in adolescents. Patients<19 years of age undergoing bariatric surgery at 5 centers between 2007 and 2012 were enrolled. Trained study staff collected baseline and postoperative anthropometric and clinical data. Presence and severity of UI were determined by standardized interview.
Results:
A total of 242 patients (76% female) were evaluated at baseline. The mean age was 17.1 years at baseline, and 72% were of white race. The preoperative median body mass index was 50.5 kg/m(2). At baseline, 18% of females and 7% of males reported UI. Prediction analysis at baseline indicated that females, white race, and increasing body mass index had greater odds for UI. UI prevalence in females and males decreased to 7% and 0%, respectively, at 6 months after surgery (P<.01) and remained stable out to 36 months postoperatively. Furthermore, older patients were less likely to achieve 3-year UI remission or improvement.
Conclusions:
In adolescents undergoing bariatric surgery, UI was more common in females than in males. Incontinence status significantly improved by 6 months and was durable to 3 years after surgery, suggesting that bariatric surgery favorably affects anatomic or physiologic mechanisms of bladder control in both males and females.
Urinary stone disease is an increasingly prevalent condition for many patients under the care of GPs. Recognizing the importance of lifestyle factors on stone development will enable GPs to manage their ‘at-risk’ patients more effectively. The aim of this article is to describe the important lifestyle factors that when modified will reduce both patients' risk of stone development and recurrence. Furthermore, the significance of stone disease as a marker of more systemic diseases, such as metabolic syndrome, is highlighted.
Obesity is an important medical problem that is rapidly approaching epidemic status. As diet and lifestyle changes can be ineffective at producing long-term weight loss, bariatric surgical procedures have become increasingly applicable to the management of obesity. Recent evidence suggests that certain types of bariatric procedures will induce lithogenic metabolic changes, and have been associated with increased risk of kidney stone formation. Specifically, Roux-en-Y gastric bypass procedures appear most likely to increase risk of urinary stone disease. In these patients, identification of metabolic abnormalities is important to therapeutically modify these risk factors. In doing so, the likelihood of stone formation may be reduced. © Springer Science+Business Media New York 2014. All rights are reserved.
Obesity is an overwhelming epidemic with implications for all aspects of medicine. Urology is no exception, and specifically obesity has had a pronounced effect on stone disease. Obese patients are at a greatly increased risk for all stones, but particularly uric acid stones. The understanding of the physiology of urolithiasis in obese patients will improve both the prevention and medical treatment of stones. Currently, surgery is the definite treatment, but obstacles exist that complicate surgery in obese persons. A review of the literature, experience of urologists, and current recommendations for accommodations for obese patients are described here within.
Purpose:
With a rising incidence of obesity and urolithiasis, we wanted to look at the outcomes of ureteroscopy for stone management in this group of patients.
Methods:
We did a systematic review of literature in accordance with Cochrane review and PRISMA guidelines on all English language articles between 1990 and June 2015 for ureteroscopy and stone treatment in obese patients. Data was retrieved for patient and stone demographics, outcomes of ureteroscopy, complications and follow-up.
Results:
Fifteen studies (835 patients) were identified with a mean age of 49 years and a mean BMI of 40.5kg/m2. The overall stone size was 14.2 mm (range:3-72 mm) with almost a third of the stones in the lower pole. The initial and final stone free rate (SFR) was 76.9% and 82.5% respectively with an overall complication rate of 9.3% (n=78). Except one patient with myocardial infraction, all other complications were Clavien grade I-III. The complication rate for morbidly obese patients (17.6%) was twice that of the obese patients (8.4%), although they were all graded as Clavien I or II.
Conclusion:
Ureteroscopy and stone fragmentation is a safe and efficient treatment method of treatment in obese patients with a good SFR and a relatively low complication rate, although the complications tend to be higher in the morbidly obese patients.
Material and methods:
We retrospectively reviewed the records of patients with urolithiasis and , concomitant hypocitraturia and low urine pH as unique abnormalities upon metabolic evaluation treated exclusively with potassium citrate. The cohort was divided into 4 groups based on body mass index (BMI): normal weight, overweight, obese and morbidly obese. Metabolic data was compared between the 4 groups at baseline and subsequent follow up visits up to 2 years. We compared urinary pH and citrate both in absolute values and the relative change in these parameters from baseline. Similarly, we compared the rates of potassium citrate treatment failure.
Results:
A total of 125 patients with both hypocitraturia and low urine pH were included in this study. Median patient age was 61 years, 80 were males and median BMI was 30.4kg/m(2) . Patients with higher BMI tended to be younger (p=0.010), had lower urinary citrate, but higher sodium, oxalate and uric acid levels whereas urine pH was similar across BMI groups. The pH values and their absolute change from baseline were lower as BMI increased (p≤0.001). Similarly, we noted an association between increasing BMI category and lower urinary citrate levels accompanied by a statistically significant trend indicating lower absolute changes in citrate with increasing BMI (p≤0.001). Potassium citrate dose was increased more frequently among the higher BMI groups.
Conclusion:
Patients with higher BMI presented lower increase in citrate excretion and urine pH levels after they were started on potassium citrate and they needed more frequently adjustments of their therapy.
Introduction:
Prevalence of the kidney stones (renal calculi) increase in several countries in parallel with the increase of overweight, diabetes (type 2 diabetes) and hypertension.
Goal:
The goal of our research was to evaluate the connection between the calcium nephrolithiasis and overweight, as quantified using the Body Mass Index (BMI) of the adult population, with a particular reflection on the age groups within it.
Material and methods:
The research was prospective and it was implemented at the Clinical Center of Banja Luka, at the Urology Clinic in the period from 1st April 2012 to 1st January 2013. The trial encompassed 120 patients with calcium nephrolithiasis of the upper part of the urinary tract and 120 patients without nephrolithiasis. A group of patients with the calcium nephrolithiasis presented a working group, while a group of patients without nephrolithiasis presented a control group. The BMI obtained on the basis of bodily weight and height of the patient, where the age and sex of specific reference values of the BMI were developed by the Center for Disease Control and Prevention (CDC) were not used in the calculation of the BMI.
Results:
Analyzing the values of the BMI in relation to age groups, where there was a statistically significant difference in the working group, whereas in the control group there was a statistically high significant difference, testing of statistical significance of the average value of the BMI was done by observed age groups of working and control group, as well as to the total sample of work and control group using the Chi-Square test and T-test for independent samples. Having observed the age group of 20-40 years, statistically significant differences have been noted at the level of risk of 10%, which confirms that there is a connection between the categories of the BMI and the group, which the patient comes from (Chi-Square test p-0.05), that is, T-test has shown that the values are different at the level of 10%, i.e. p<0.1 (p=0.073). Having observed the age group 40-60, there was no dependency between the category of the BMI and the group, that is, the differences are not statistically significant, p>0.05 (t-test p=0.314). In addition to this, the average BMI values are not significantly different, p>0.05 (t-test p=0.871). Having observed the age group of the older than 60, there was no dependency between the category of the BMI and the group, that is, the differences are not statistically significant, p>0.05 (Chi-square test p=0.167). Having observed the total sample of the working and control group, there was no dependency of the category of the BMI and the group (or urolithiasis), p>0.05 (Chi-Square test p=1.208), whereas the results of the T-test showed that there was no statistically significant difference of the arithmetic mean values of the BMI working group and control group, p>0.05 (t-test p=0.620).
Conclusion:
Overweight in younger age groups of adult population may be connected to the occurrence of calcium nephrolithiasis, thus we suggest that urolithiasis should be considered with them, as part of overweight, by which a change of living habits and the manner of food consumption could prevent this disease.
Retrograde ureterorenoscopy (URS) is a standard treatment approach for renal and ureteral stones, as well as for other upper tract pathology like ureteral stricture disease and transitional cell carcinoma. Obese patients present unique challenges for treatment of stone disease in particular, as shock wave lithotripsy (SWL) has a higher risk of failure in these patients, and percutaneous nephrolithotomy (PNL) may present technical challenges based on large body habitus. URS, then, may be the preferred approach in patients with significant obesity, though there may be anesthesia and surgical challenges to this procedure as well. URS may also be the treatment of choice in patients with bleeding disorders, or those who are anticoagulated, based on bleeding risks associated with alternative modalities (e.g., SWL and PNL). Refinements in ureteroscope and laser technology have enabled safe therapeutic interventions in this population despite their propensity for bleeding. Care to minimize trauma to the upper tract during these interventions is necessary to ensure treatment safety and efficacy.
Diabetes mellitus (DM) might increase the risk of urolithiasis, but the results were inconsistent. Hence, we conducted a meta-analysis to assess the association between DM and the risk of urolithiasis. We searched PubMed, Embase, and Cochrane Library to identify the relevant observational studies up to November 2014. Reference lists of retrieved articles were also reviewed. Summary relative risks (RRs) and corresponding 95 % confidence intervals (CIs) were used to estimate the association between DM and the risk of urolithiasis. We identified 3 case-control studies and 4 cohort studies regarding DM and the risk of urolithiasis, involving 247,531 participants. Analyses of all studies showed that DM was associated with an increased risk of urolithiasis (RR = 1.24, 95 % CI: 1.14-1.35). There was heterogeneity among studies (p = 0.027, I (2) = 57.9 %). The association between DM and the risk of urolithiasis was not significantly differed by gender, but this association was inconsistent in the North American and Asian populations. When restricting the analysis to studies that had adjusted for body mass index (n = 2) or hypertension (n = 3), the RRs were 1.46 (95 % CI: 1.03-2.06) and 1.22 (95 % CI: 1.01-1.48), respectively. There was no significant publication bias (p = 0.96 for Egger's regression asymmetry test). Our study provided evidence that there was a significant direct association of DM and the risk of urolithiasis. However, this finding was based on the observational studies, and more well-designed randomized controlled trials were needed.
Although there is growing evidence of relationship between obesity and some specific stone compositions, results were inconsistent. Due to a greater relationship between metabolic syndrome and some specific stone type, obesity measured by body mass index (BMI) has limitation in determining relationship between obesity and stone compositions. The aim of this study was to determine the relationship among BMI, visceral fat, and stone compositions.
We retrospectively reviewed data of patients with urinary stone removed over a 5 year period (2011-2014). Data on patient age, gender, BMI, urinary pH, stone composition, fat volumes (including visceral fat, subcutaneous fat, total fat, waist circumference), and ratio for visceral to total fat using computed tomography based delineation were collected. To figure out the predicting factor while adjusting other confounding factors, discriminant analysis was used.
Among 262 cases, average age was 52.21 years. Average BMI and visceral fat were 25.03 cm(2) and 124.75 cm(2), respectively. By chi square test, there was significant (p < 0.001) difference in stone types according to sex. By ANOVA test, BMI, visceral fat, visceral to subcutaneous fat ratio, the percentage of visceral fat and total fat showed significant association with stone types. By discriminant analysis, visceral fat was proved to be a powerful factor to predict stone composition (structure matrix of visceral fat = -0.735) with 42.0% of predictive value.
Visceral fat adiposity strongly related with uric acid stone and has better predictive value than BMI or urinary pH to classify the types of stone.
Goal: Determine correlation between complications and stage of the disease and their impact on quality of life in patients with different types of ileal urinary derivation after radical cystectomy, and upon estimation of acquired results, to suggest the most acceptable type of urinary diversion.
Patients and methods: In five year period a prospective clinical study was performed on 106 patients, to whom a radical cystectomy was performed due to bladder cancer. Patients were divided into two groups, 66 patients with ileal conduit derivation and 40 patients with orthotopic derivation, whereby in each group a comparison between reflux and anti-reflux technique of orthotopic bladder was made. All patients from both groups filled the Sickness Impact Profile score six months after the operation. All patients had CT urography or Intravenous urography performed, as well as standard laboratory, vitamin B12 blood values, in order to evaluate early (ileus or subileus, wound dehiscence, bladder fistula, rupture of orthotopic bladder, urine extravazation) and late complications (VUR, urethral stricture, ureter stenosis, metabolic acidosis, mineral dis-balance, hypovitaminosis of vitamin B12, increased resorption of bone calcium, urinary infection, kidney damage, relapse of primary disease), so as disease stage and it's impact on quality of life.
Results: From gained results we observe that each category of SIP score correlates with different rate of correlation with the type of operation, group, T, N, and R grade, except work category. Average value of SIP score rises depending on the type of operation and T stage. It is notable that there is no difference in T1 stage, no matter the type of operation. So the average value of SIP score in T1 stage for conduit was 20.3, for Abol-Enein and Ghoneim 17.25 and Hautmann 18.75 respectively. Average value of SIP score in T2 stage for conduit was 31, for Abol-Enein and Ghoneim 19.1 and Hautmann 17.8. Average value of SIP score in T3 stage for conduit was 38.03, for Abol-Enein and Ghoneim 18.75 and Hautmann 19.5. SIP score for T4 was present only in patients with conduit performed and average value od SIP score was 40.42. There is a high level of correlation of late complications and psychosocial and physical dimension with their parameters, while for an independent dimension of correlation is not significant. Early complications have insignificant correlation in all categories of SIP score.
Conclusion: Upon analyzing quality of life and morbidity, significant advantage is given to orthotopic derivations, especially Hautmann derivation with Chimney modification, unless there are no absolute contraindications for performing this type of operation. Factors which mostly influence quality of life are cancer stage, type of derivation, late complications and patient age. SIP score, as a well validated questionnaire, are applicable in this kind of research.
Significant advances have taken place in medicine over the past century. In addition, increasing rates of obesity, diabetes mellitus, and metabolic syndrome have resulted in increasing rates of stones among men and women. Within 1 year of forming a calcium oxalate stone, 10 % of men will form another calcium oxalate stone, and 50 % will form another stone within 10 years.
Males are affected three times as frequently as females for stones. Testosterone clearly has an impact on this; however, the rates of nephrolithiasis among women are increasing. Urine studies have demonstrated a decrease in urinary pH (>5.5) and an increase in uric acid supersaturation. This has resulted in increased rates of uric acid stones. In addition, obesity surgery has increased the risk of calcium oxalate stone formation.
All of these factors combined have had a profound influence on the patterns of stone disease. Lifestyles have significantly affected the prevalence of kidney stone disease. In this chapter, we will review the impact of societal changes on stone patterns.
Objective
To analyze results and morbidity after flexible ureterorenoscopy (fURS) in patients with a body mass index (BMI) > 30 kg/m2 and to compare with results obtained in a large cohort of non-obese patients.
Methods
We conducted a retrospective monocenter study including all fURS for urinary lithiasis performed in our institution between January 2004 and December 2010. During the study period, 497 procedures were performed. Twenty-three had to be excluded because of missing data on BMI. Thus, a total of 474 procedures were included in the final analysis, 93 for obese patients (OP) and 381 for non-obese patients (NOP). Characteristics of the patients, stones and procedures were analyzed. Success was defined as clear imaging (completely stone-free) on renal tomography and ultrasonography.
Results
Mean BMI was 33.5 ± 0.3 in OP vs 23.9 ± 0.1 kg/m2 in NOP (P < 0.0001). Mean stone size, location, and composition were not significantly different between groups. Technical aspects (operative time, ureteral dilatation, access sheath, monobloc extraction) were also similar in OP and NOP. The immediate (63.5% for OP vs 66.1% in NOP, P = 0.62) and follow-up (65.1% for OP vs 71% in NOP, P = 0.26) stone-free rate were not significantly different between the groups. For stone size < 1 cm, SFR raised to 77% in OP vs 83% in NOP (P = 0.28). The rate of minor complications Clavien II was similar in OP (7.5%) and NOP (12%). No major complication (Clavien III or IV) was observed.
Conclusion
fURS is a safe and efficient option for the management of urinary lithiasis in obese patients.
To determine the relationship between body mass index (BMI), visceral adipose tissue (VAT), and stone components.
A cross-sectional study has been done for urinary stone cohort between 2010 and 2012. Data on patient's age, gender, BMI, urinary pH, stone components, and VAT using computed tomography-based delineation were collected. Obesity was defined as BMI ≥ 25 kg/m(2) or as VAT ≥ 100 cm(2). To compare the differences between the types of stones, multinomial logistic regression analyses were conducted.
Of 203 cases, 49.3% patients were obese based on BMI, and 65.5% were obese using VAT criteria. Multinomial logistic regression analysis revealed that obesity defined by VAT was found to be associated with uric acid stones compared with calcium phosphate stones (odds ratio [OR] 6.544, 95% confidence interval [CI], P = .030) and mixed calcium oxalate phosphate stones (OR 5.582, 95% CI, P = .038). Similar results were observed in calcium oxalate stones over calcium phosphate stones (OR 2.984, 95% CI, P = .032) and calcium oxalate phosphate stones (OR 2.542, 95% CI, P = .041). On the contrary, obesity defined based on BMI has no correlation over all types of urinary stone components.
This result implies that VAT has a more important role in uric acid and calcium oxalate stone formation than total body fat, represented by BMI.
To review the recent publications describing the link between pediatric nephrolithiasis and bone metabolism.
Nephrolithiasis incidence is increasing in children and is associated with low bone mineral density (BMD). Affected children are conceptually at risk for fractures and osteoporosis. In addition to abnormal calcium metabolism, inflammation, genetic makeup and dietary habits are being recognized as important factors in the pathophysiology of nephrolithiasis and low bone density. Findings from retrospective reviews suggest that low BMD in children may be improved with citrate or thiazide treatment.
The healthcare burden from low BMD with subsequent osteoporosis and fracture risk is immense with potential far-reaching effects in patient quality of life and healthcare expense. Bone mass is acquired in the pediatric age range, thus it is important to identify and treat at-risk children. Retrospective reviews in pediatric patients indicate that citrate or thiazide diuretic treatment may improve BMD. We now understand that a relationship exists between nephrolithiasis and low BMD. To improve healthcare for our current patients as well as protect their future health it is important to identify low BMD and initiate strategies to improve BMD in 'at-risk' children.
The incidence of urolithiasis is worldwide increasing and contributes to a rising economic and health care burden. The objective of this review is to identify gender differences in urolithiasis epidemiology in Europe and the USA as well as gender-specific risk factors for urolithiasis.
A systematic review of the present literature was performed including English journals without a time limit. The MeSH terms used were as follows: ("Sex Characteristics"[Mesh]) AND "Urolithiasis"[Mesh] or ("Epidemiology"[Mesh]) AND "Urolithiasis"[Mesh]. Additionally, reference search of retrieved papers identified additional references. The MEDLINE database was searched.
The prevalence of urolithiasis is rising worldwide including both genders in different age groups. Especially women face an increase in prevalence in the USA. Overweight seems to be an important cause for this development. Additionally insulin resistance and hypertonia, conditions present in the metabolic syndrome complex, contribute to this phenomenon.
Stone prevalence across all age groups and both genders is increasing. Lifestyle changes along with increasing prevalence of obesity are key factors for this development. Female gender did significantly differ in the risk ratio of stone development in different variables including body mass index, hyperinsulinemia, and hypertension. It is important to inform the public on measures how to change lifestyle and dietary measures for preventing or lowering events of stone disease.
Bariatric surgery is now recognized as a sure and effective way for weight reduction in morbid obesity. However some procedures induce intestinal malabsorption leading to enteric hyperoxaluria. So bariatric surgery could place these patients not only at risk for nephrolithiasis but also for oxalate induced nephropathy and chronic renal failure. Because of the growing incidence of obesity worldwide, physicians and patients should be aware of such potential complications. There is no mean to discuss this treatment because of its spectacular efficiency on obesity and its comorbidities. But it is necessary to choose the surgical technique according to the risk factors of the patients. Following surgery, preventive treatment strategies are indicated, such as modified dietary lifestyle and specific drugs as we suggested to limit or even avoid these complications. However observance could fail in the long term. In case of oxalate nephropathy, surgery may be proposed to restore the intestinal tract but with the risk of overweight relapse. To illustrate this matter, we report here significant observations of three patients, which, having successfully benefited from the same bariatric surgery, have presented lithiasic complications for two of them and oxalate nephropathy leading to chronic renal failure and hemodialysis for the third.
The aim of the study to compare outcomes of flexible ureterorenoscopy in patients with different body mass index (BMI) scores and to explore whether the BMI has an effect on outcomes of RIRS. Five hundred and two patients who underwent flexible URS in 3 centers between 2008 and 2012 for the management of single upper urinary tract calculi were retrospectively reviewed. Patients were categorized as normal weight BMI 18.5 to 24.99 kg/m(2), overweight 25 to 29.99 kg/m(2), obese 30 to 39.99 kg/m(2) and morbid obese >40 kg/m(2).The groups were assessed in terms of demographic parameters including age, gender, stone size, intraoperative and postoperative variables. The mean patient age was 41.3 ± 15.51 (18-81) years and with an average BMI 26.68 ± 5.2 kg/m(2) (16.64-55.15 kg/m²). Of the patients, 43.2 % had normal weight (NW), 32.2 % were overweight (OW), 21.9 % were obese (O) and 2.5 % were morbidly obese (MO). Stone-free rates after single procedure in NW, OW, O, MO groups were 60.8, 61.7, 73.6, 61.5 %, respectively (p = 0.079). Overall targeted stone-free rates were also similar in four groups (88.9, 90.1, 93.6, 90.4 %, p = 0.586). There were no statistically significant differences in the frequency of complications and mean hospitalization time among the groups (p > 0.05). In conclusion, this study demonstrated that flexible URS is a valuable option for the treatment of kidney stone in both obese and non-obese patients. BMI did not influence the postoperative outcomes.
Objective:
Surgical treatment of kidney stones in an obese patient (body mass index [BMI] >30 kg/m(2)) remains challenging as shockwave lithotripsy may not be an option due to weight limitations. We sought to determine the effectiveness of ureteroscopic laser lithotripsy in obese patients compared to nonobese controls.
Materials and methods:
Patients from 2004 to 2007 were retrospectively analyzed providing a group of 292 patients (163 obese, 76 overweight, 53 normal) who underwent ureteroscopic procedures for urolithiasis at four centers in the United States and Canada.
Results:
The percentage of obese patients requiring flexible ureteroscopy (URS) (79%) was higher than in the other groups (P<0.0001). Flexible URS was associated with a lower stone-free rate (SFR) on multivariate analysis (P=0.034). There was no difference in SFRs of patients who required a ureteral access sheath, basket extraction, or received a postoperative stent. Complication rates did not differ between groups.
Conclusion:
SFRs using ureteroscopic lithotripsy in obese and overweight populations are the same as in the normal weight patients. A flexible ureteroscope was associated with a decreased SFR, but this likely due to a more proximal stone location in these patients. Ureteroscopic laser lithotripsy is an effective and safe technique to treat urolithiasis in the overweight/obese patient.
Background:
The objective of this study was to assess predictors for new-onset stone formers after Roux-en-Y gastric bypass (RYGBP).
Methods:
One hundred and fifty-one obese patients underwent RYGBP and were followed for 1 year. The analysis comprised two study time points: preoperative (T0) and 1 year after surgery (T1). They were analyzed for urinary stones, blood tests, and 24-h urinary evaluation. Nonparametric tests, logistic regression, and multivariate analysis were conducted using SPSS 17.
Results:
Median BMI decreased from 44.1 to 27.0 kg/m2 (p < 0.001) in the postoperative period. Urinary oxalate (24 versus 41 mg; p < 0.001) and urinary uric acid (545 versus 645 mg; p < 0.001) increased significantly postoperatively (preoperative versus postoperative, respectively). Urinary volume (1310 versus 930 ml; p < 0.001), pH (6.3 versus 6.2; p = 0.019), citrate (268 versus 170 mg; p < 0.001), calcium (195 versus 105 mg; p < 0.001), and magnesium (130 versus 95 mg; p = 0.004) decreased significantly postoperatively (preoperative versus postoperative, respectively). Stone formers increased from 16 (10.6 %) to 27 (17.8%) patients in the postoperative analysis (p = 0.001). Predictors for new stone formers after RYGBP were postoperative urinary oxalate (p = 0.015) and uric acid (p = 0.044).
Conclusions:
RYGBP determined profound changes in urinary composition which predisposed to a lithogenic profile. The prevalence of urinary lithiasis increased almost 70% in the postoperative period. Postoperative urinary oxalate and uric acid were the only predictors for new stone formers.
To determine which metabolic syndrome (MetS) factors lead to differences in stone composition in a multivariate analysis.
We retrospectively reviewed medical charts of patients who had a kidney stone removed over a 5-year period (2006-2011). MetS factors (obesity [body mass index {BMI} >30], diabetes mellitus [DM], hypertension [HTN], and dyslipidemia [DLD]) were tallied in each patient. For the latter 3 factors, medical treatment for the condition was used to tag a patient with the condition. Stone composition was determined by the dominant (>50%) component. Statistical analysis was designed to determine which MetS factors were independently associated with differences in stone composition.
Five hundred ninety kidney stones were included in the analysis. Patients with MetS had a higher prevalence of uric acid stones and lower prevalence of calcium phosphate stones. HTN and DM were independently associated with differences in composition, specifically uric acid stones (higher proportion), and calcium phosphate stones (lower proportion). Obesity was not associated with differences in composition, although a secondary analysis of morbidly obese patients showed a higher proportion of uric acid stones and a lower proportion of calcium oxalate stones.
HTN and DM are the MetS factors independently associated with differences in stone composition, specifically the uric acid and calcium phosphate components. Obesity has little effect on stone composition until a very high (>40) BMI is reached. The overall effect of MetS factors on stone type is relatively small, because most stones are calcium oxalate and MetS factors have little impact on calcium oxalate frequency.
Study Type – Prognosis (systematic review)
Level of Evidence 1a
What's known on the subject? and What does the study add?
Case series on ureteroscopy for obese patients have been published in the literature, but as yet no decisive conclusion has been published because of the small patient numbers included the study cohorts.
This review provides an overview of the literature discussing ureteroscopy for obese patients. In addition, it provides a meta-analysis of the case series and published literature on the topic, which focuses on the safety and efficacy of ureteroscopy for obese patients.
The aim of the study was to analyze results and morbidity after flexible ureterorenoscopy in patients with a body mass index (BMI) >30 kg/m(2) and to compare with results obtained in a large cohort of nonobese patients.
We conducted a retrospective study including all flexible ureterorenoscopy performed for stone retrieval in our institution between January 2004 and December 2008. During the study period, 224 procedures were performed, of which 18 had to be excluded because of missing BMI data. Thus, a total of 206 procedures were included in the final analysis (34 in 29 obese patients, 172 in 149 nonobese patients). Characteristics of the patients (age, BMI, previous treatment), stones (nature, location, number), and procedures (operating time, morbidity, outcome) were analyzed. Success was defined as clear imaging (completely stone free) on renal tomography and ultrasonography at 1, 3, and 6 months follow-up.
Mean BMI was 34±0.6 kg/m(2) in obese patients (OP) and 24±0.2 kg/m(2) in nonobese patients (NOP). Mean stone size, location, and composition were not significantly different between groups. Operative time was also similar in OP and NOP (102.5±6.1 min vs 103±3.4 min, P=NS). The rate of minor complications (fever, hematuria, flank pain) was similar in OP (11.8%) and NOP (11.4%). No major complication necessitating prolonged hospital stay or new surgical procedure was observed. The overall stone-free rate was not significantly different between OP (79.4%) and NOP (70%).
Flexible ureterorenoscopy is an appropriate treatment for use in obese patients and achieves excellent stone-free rates with low morbidity.
We analyzed differences in urinary stone composition according to body mass index (BMI).
Between January 2007 and December 2010, 505 ureteral or renal stones were collected from 505 patients who underwent surgical intervention. Data on patient age, gender, BMI, urinary pH, and stone composition were collected.
The patients' mean age was 49.2 years (range, 20 to 83 years). Of the 505 patients, 196 (38.7%) had calcium oxalate (CO) stones, 172 (33.9%) had mixed calcium oxalate and calcium phosphate (COP) stones, 72 (14.2%) had calcium phosphate (CP) stones, 50 (9.8%) had uric acid (UA) stones, and 15 (2.9%) had struvite stones. We excluded struvite stones in the statistical analysis because of the small number of patients; a total of 490 patients were included in this study. In the multinomial logistic regression analysis, obesity was found to be associated with UA stones compared with COP stones (odds ratio [OR] 3.488; 95% confidence interval [CI] 1.732-7.025; p<0.001) and CP stones (OR 2.765; 95% CI 1.222-6.259; p=0.015). Similar results were observed for CO stones compared with COP stones (OR 2.682; 95% CI 1.727-4.164; p<0.001) and CP stones (OR 2.126; 95% CI 1.176-3.843; p<0.013).
Obesity was associated with UA and CO stones compared with the occurrence of COP and CP stones.
From the analysis of various urinary constituents and the estimation of urinary saturation of stone-forming salts, it is now possible to identify risk factors responsible for or contributing to stone formation. Metabolic factors included calcium, oxalate, uric acid, citrate and pH. Environmental factors were total volume, sodium, sulfate, phosphate and magnesium. Physicochemical factors represented saturation of calcium oxalate, brushite, monosodium urate, struvite and uric acid.
A variety of factors influence the formation of calcium oxalate kidney stones, including gender, diet, and urinary excretion of calcium, oxalate, and uric acid. Several of these factors may be related to body size. Because men on average have a larger body size and a threefold higher lifetime risk of stone formation than women, body size may be an important risk factor for calcium oxalate stone formation. The association between body size (height, weight, and body mass index) and the risk of kidney stone formation was studied in two large cohorts: the Nurses' Health Study (NHS; n = 89,376 women) and the Health Professionals Follow-up Study (HPFS; n = 51,529 men). Information on body size, kidney stone formation, and other exposures of interest was obtained by mailed questionnaires. A total of 1078 incident cases of kidney stones in NHS during 14 yr of follow-up and a total of 956 cases in HPFS during 8 yr of follow-up were confirmed. In both cohorts, the prevalence of a stone disease history and the incidence of stone disease were directly associated with weight and body mass index. However, the magnitude of the associations was consistently greater among women. Specifically, the age-adjusted prevalence odds ratio for women with body mass index > or = 32 kg/m2 compared with 21 to 22.9 kg/m2 was 1.76 (95% confidence interval, 1.50 to 2.07), but 1.38 (95% confidence interval, 1.16 to 1.65) for the same comparison in men. For incident stone formation, the multivariate relative risks for the similar comparisons were 1.89 (1.51 to 2.36) for women and 1.19 (0.83 to 1.70) in men. Height was inversely associated with the prevalence of stone disease but was not associated with incident stone formation. These results suggest that body size is associated with the risk of stone formation and that the magnitude of risk varies by gender. Additional studies are necessary to determine whether a reduction in body weight decreases the risk of stone formation, particularly in women.
Patients with renal failure are characterized by impaired insulin-mediated glucose uptake. Insulin plays a major role in the maintenance of phosphate homeostasis but it remains to be determined whether in uraemia insulin-dependent renal and extrarenal phosphate disposal is also affected.
The effect of hyperinsulinaemia on serum concentrations of phosphate, ionized calcium and intact PTH as well as renal excretion of calcium and phosphate was studied under euglycaemic conditions (glucose clamp technique) in patients with advanced renal failure and in healthy subjects. Fifteen patients with renal failure (mean serum creatinine 917 micromol/l) and 12 control subjects were included. All subjects underwent a 3-h euglycaemic clamp with constant infusion of insulin (50 mU/m2/min) following a priming bolus. The urine was collected for 3 h before and throughout the clamp.
The tissue insulin sensitivity (M/I) was lower in patients with renal failure than in control subjects (5.3+/-2.4 vs 6.7+/-1.8mg/kg/min per mU/ml, P= 0.001) but the phosphate lowering action of insulin was larger in patients with renal failure than in control subjects. Urinary calcium excretion increased (P < 0.05) and phosphate excretion did not change during the clamp in both groups. Despite a decrease of serum ionized calcium in the group of patients with renal failure and no change in the control group, plasma PTH fell significantly in both groups but this effect was still significant after 180 min only in the renal failure group. A significant correlation was observed between changes in serum phosphate and PTH induced by hyperinsulinaemia (r = 0.48, P < 0.01 )
Phosphate-lowering effect of insulin is well preserved in severe renal failure despite the resistance to insulin-stimulated glucose uptake. The decrease of serum PTH observed during hyperinsulinaemia appears to be independent of serum ionized calcium.
The aim of the study was to assess the influence of overweight and obesity on the risk of calcium oxalate stone formation.
BMI, 24-hour urine, and serum parameters were evaluated in idiopathic calcium oxalate stone formers (363 men and 164 women) without medical or dietetic pretreatment.
Overweight and obesity were present in 59.2% of the men and in 43.9% of the women in the study population. Multiple linear regression analysis revealed a significant positive relationship between BMI and urinary uric acid, sodium, ammonium, and phosphate excretion and an inverse correlation between BMI and urinary pH in both men and women, whereas BMI was associated with urinary oxalate excretion only among women and with urinary calcium excretion only among men. Serum uric acid and creatinine concentrations were correlated with BMI in both genders. Because no association was established between BMI and urinary volume, magnesium, and citrate excretion, inhibitors of calcium oxalate stone formation, the risk of stone formation increased significantly with increasing BMI among both men and women with urolithiasis (p = 0.015). The risk of calcium oxalate stone formation, median number of stone episodes, and frequency of diet-related diseases were highest in overweight and obese men.
Overweight and obesity are strongly associated with an elevated risk of stone formation in both genders due to an increased urinary excretion of promoters but not inhibitors of calcium oxalate stone formation. Overweight and obese men are more prone to stone formation than overweight women.
The increasing prevalence and associated sociodemographic disparities of morbid obesity are serious public health concerns. Bariatric surgical procedures provide greater and more durable weight reduction than behavioral and pharmacological interventions for morbid obesity.
To examine trends for elective bariatric surgical procedures, patient characteristics, and in-hospital complications from 1998 to 2003 in the United States.
The Nationwide Inpatient Sample was used to identify bariatric surgery admissions from 1998-2002 (with preliminary data for 12 states from 2003) using International Classification of Diseases, Ninth Revision, codes for foregut surgery with a confirmatory diagnosis of obesity or by diagnosis related group code for obesity surgery. Annual estimates and trends were determined for procedures, patient characteristics, and adjusted complication rates.
Trends in bariatric surgical procedures, patient characteristics, and complications.
The estimated number of bariatric surgical procedures increased from 13,365 in 1998 to 72,177 in 2002 (P<.001). Based on preliminary state-level data (1998-2003), the number of bariatric surgical procedures is projected to be 102 794 in 2003. Gastric bypass procedures accounted for more than 80% of all bariatric surgical procedures. From 1998 to 2002, there were upward trends in the proportion of females (81% to 84%; P = .003), privately insured patients (75% to 83%; P = .001), patients from ZIP code areas with highest annual household income (32% to 60%, P<.001), and patients aged 50 to 64 years (15% to 24%; P<.001). Length of stay decreased from 4.5 days in 1998 to 3.3 days in 2002 (P<.001). The adjusted in-hospital mortality rate ranged from 0.1% to 0.2%. The rates of unexpected reoperations for surgical complications ranged from 6% to 9% and pulmonary complications ranged from 4% to 7%. Rates of other in-hospital complications were low.
These findings suggest that use of bariatric surgical procedures increased substantially from 1998 to 2003, while rates of in-hospital complications were stable and length of stay decreased. However, disparities in the use of these procedures, with disproportionate and increasing use among women, those with private insurance, and those in wealthier ZIP code areas should be explored further.
The prevalence of overweight in children and adolescents and obesity in adults in the United States has increased over several decades.
To provide current estimates of the prevalence and trends of overweight in children and adolescents and obesity in adults.
Analysis of height and weight measurements from 3958 children and adolescents aged 2 to 19 years and 4431 adults aged 20 years or older obtained in 2003-2004 as part of the National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the US population. Data from the NHANES obtained in 1999-2000 and in 2001-2002 were compared with data from 2003-2004.
Estimates of the prevalence of overweight in children and adolescents and obesity in adults. Overweight among children and adolescents was defined as at or above the 95th percentile of the sex-specific body mass index (BMI) for age growth charts. Obesity among adults was defined as a BMI of 30 or higher; extreme obesity was defined as a BMI of 40 or higher.
In 2003-2004, 17.1% of US children and adolescents were overweight and 32.2% of adults were obese. Tests for trend were significant for male and female children and adolescents, indicating an increase in the prevalence of overweight in female children and adolescents from 13.8% in 1999-2000 to 16.0% in 2003-2004 and an increase in the prevalence of overweight in male children and adolescents from 14.0% to 18.2%. Among men, the prevalence of obesity increased significantly between 1999-2000 (27.5%) and 2003-2004 (31.1%). Among women, no significant increase in obesity was observed between 1999-2000 (33.4%) and 2003-2004 (33.2%). The prevalence of extreme obesity (body mass index > or =40) in 2003-2004 was 2.8% in men and 6.9% in women. In 2003-2004, significant differences in obesity prevalence remained by race/ethnicity and by age. Approximately 30% of non-Hispanic white adults were obese as were 45.0% of non-Hispanic black adults and 36.8% of Mexican Americans. Among adults aged 20 to 39 years, 28.5% were obese while 36.8% of adults aged 40 to 59 years and 31.0% of those aged 60 years or older were obese in 2003-2004.
The prevalence of overweight among children and adolescents and obesity among men increased significantly during the 6-year period from 1999 to 2004; among women, no overall increases in the prevalence of obesity were observed. These estimates were based on a 6-year period and suggest that the increases in body weight are continuing in men and in children and adolescents while they may be leveling off in women.
Roux-en-Y bypass surgery is the most common bariatric procedure currently performed in the United States for medically complicated obesity. Although this leads to a marked and sustained weight loss, we have identified an increasing number of patients with episodes of nephrolithiasis afterwards. We describe a case series of 60 patients seen at Mayo Clinic-Rochester that developed nephrolithiasis after Roux-en-Y gastric bypass (RYGB), including a subset of 31 patients who had undergone metabolic evaluation in the Mayo Stone Clinic. The mean body mass index of the patients before procedure was 57 kg/m(2) with a mean decrease of 20 kg/m(2) at the time of the stone event, which averaged 2.2 years post-procedure. When analyzed, calcium oxalate stones were found in 19 and mixed calcium oxalate/uric acid stones in two patients. Hyperoxaluria was a prevalent factor even in patients without a prior history of nephrolithiasis, and usually presented more than 6 months after the procedure. Calcium oxalate supersaturation, however, was equally high in patients less than 6 months post-procedure due to lower urine volumes. In a small random sampling of patients undergoing this bypass procedure, hyperoxaluria was rare preoperatively but common 12 months after surgery. We conclude that hyperoxaluria is a potential complicating factor of RYGB surgery manifested as a risk for calcium oxalate stones.
We explored the effects of insulin on mineral homeostasis in five lean and six moderately obese nondiabetic premenopausal women. Serum and urine minerals were measured before and during the steady-state phase of a euglycemic insulin clamp. Each subject participated in two insulin clamp studies on separate days at insulin infusion rates of 10 and 40 mU/m2/min. Euglycemic hyperinsulinemia was associated with (1) a significant increase in urinary calcium excretion when expressed per minute with no change in total serum calcium; (2) a decrease in urine and serum phosphate; (3) a decrease in serum potassium with no change in urine potassium; and (4) no measurable effects on urine or serum sodium. At any given insulin level, the obese individuals excreted significantly more calcium, phosphate, and potassium per minute than lean controls. While insulin administration had no effect on serum parathyroid hormone (PTH) or vitamin D levels, baseline serum 1,25(OH)2D concentration was significantly higher and serum ultrafilterable calcium was significantly lower in obese subjects than in lean controls.
From the analysis of various urinary constituents and the estimation of urinary saturation of stone-forming salts, it is now possible to identify risk factors responsible for or contributing to stone formation. Metabolic factors included calcium, oxalate, uric acid, citrate and pH. Environmental factors were total volume, sodium, sulfate, phosphate and magnesium. Physicochemical factors represented saturation of calcium oxalate, brushite, monosodium urate, struvite and uric acid. A scheme for graphic display of risk factors was developed to allow ready visual recognition of important risk factors presumed to cause stone formation. This graphic display had diagnostic use as well as practical value in following response to treatment. For example, a low urinary pH and high urinary concentration of undissociated uric acid could be discerned readily in cases of uric acid lithiasis, as were high urinary pH and exaggerated urinary supersaturation of struvite in cases of infection lithiasis. In a patient with absorptive hypercalciuria and hypocitraturia treatment with thiazide and potassium citrate could be shown to abolish high risks (hypercalciuria, hypocitraturia and relative supersaturation of calcium oxalate) displayed before treatment.
Obesity increases the risk of developing chronic medical conditions such as diabetes mellitus, hypertension, and coronary artery disease. We performed a retrospective review of a large data base on urinary stones to determine if differences are found in urine and serum chemistries among obese and nonobese stone-forming patients. The effect of body weight on stone recurrence among urinary stone formers was also determined.
A national data base containing serum biochemical profiles, 24-hour urine specimens, and standardized questionnaires was retrospectively evaluated from 5942 consecutive patients with urinary stone disease. Stone-forming patients were classified by body weight: nonobese men, less than 100 kg and nonobese women, less than 85 kg; intermediate men, 100 to 120 kg and intermediate women, 85 to 100 kg; and obese men, more than 120 kg and obese women, more than 100 kg.
Obese stone formers comprised 6.8% (n = 404) of the patient population. The mean weight in the nonobese and obese groups was 81 kg versus 134 kg, respectively, for men and 64 kg versus 112 kg, respectively, for women. Obese patients represented 3.8% of the male and 12.6% of the female population. Obese patients had increased urinary excretion of sodium, calcium, magnesium, citrate, sulfate, phosphate, oxalate, uric acid, and cystine; obesity was associated with increased urinary volumes and urine osmolality compared with the nonobese patients. Obese men had increased concentration of urinary sodium, oxalate, uric acid, sulfate, and phosphate when corrected for urinary volume. Obese women had increased concentrations of sodium, uric acid, sulfate, phosphate, and cystine. The mean number of stone episodes in nonobese versus obese men was similar (3.55 and 3.56), whereas mean stone episodes were 2.93 and 3.38 (P = 0.045) for nonobese versus obese women.
Among known stone formers, obesity is associated with unique changes in both serum and urinary chemistries. These changes are associated with an increased incidence of urinary stone episodes in obese women but not in obese men.
Low urinary pH is the commonest and by far the most important factor in uric acid nephrolithiasis but the reason(s) for this defect is (are) unknown. Patients with uric acid nephrolithaisis have normal acid-base parameters according conventional clinical tests.
We studied steady-state plasma and urinary parameters of acid-base balance in subjects with normouricosuric pure uric acid stones. We also tested the ability of these subjects to excrete ammonium in response to an acute acid load. We compared these parameters in patients with pure uric acid stones to patients with mixed uric acid/calcium oxalate stones, pure calcium stones, and normal volunteers.
Pure uric acid stone formers have a much higher incidence of either diabetes or glucose intolerance. After equilibration to a control diet, patients with uric acid stones have lower urinary pH and they excrete less of their acid as ammonium. This is compensated by higher titratable acidity and hypocitraturia. Despite their low baseline urinary pH, uric acid stone formers further acidify their urine after an acid load because of a severely impaired ammonia excretory response. Their characteristics are significantly different from normal volunteers and pure calcium stone formers. Patients with mixed uric acid/calcium stones exhibit intermediate characteristics.
We propose that certain patients with normouricosuric uric acid nephrolithiasis have a renal acidification disease. The primary defect lies in renal ammonium excretion, which may be linked to the insulin-resistant state. Although net acid excretion is maintained at the expense of increased titratable acidity and to some degree hypocitraturia, the compromise is acid urine pH and may result in uric acid nephrolithiasis.
Uric acid nephrolithiasis primarily results from low urinary pH, which increases the concentration of the insoluble undissociated uric acid, causing formation of both uric acid and mixed uric acid/calcium oxalate stones. These patients have recently been described as exhibiting features of insulin resistance. This study was designed to evaluate if insulin resistance is associated with excessively low urinary pH in overtly healthy volunteers (non-stone formers) and if insulin resistance may explain the excessively low urinary pH in patients with uric acid nephrolithiasis.
Fifty-five healthy volunteers (non stone-formers) with a large range of body mass index and 13 patients with recurrent uric acid nephrolithiasis underwent hyperinsulinemic euglycemic clamp, 24-hour urinary studies, and anthropometric measurements of adiposity. A subgroup of 35 non-stone formers had 2-hour timed urinary collection before and during the hyperinsulinemic phase of the clamp studies.
For the non-stone former population, low insulin sensitivity measured as glucose disposal rate significantly correlated with low 24-hour urinary pH (r= 0. 35; P= 0.01). In addition to the previously described acidic urine pH and hypouricosuria, patients with recurrent uric acid nephrolithiasis were found to be severely insulin resistant (glucose disposal rate: uric acid stone-formers vs. normals; 4.1 +/- 1.3 vs. 6.9 +/- 2.1 mg/min/kg of lean body mass, P= 0.008). Acute hyperinsulinemia was associated with higher urinary pH (6.1 +/- 0.7 at baseline to 6.8 +/- 0.7 during hyperinsulinemia; P < 0.0001), urinary ammonia excretion (2.7 +/- 1.6 mEq/2 hr at baseline and 4.0 +/- 2.6 mEq/2 hr P= 0.002) and urinary citrate excretion (48 +/- 33 mg/2 hr at baseline and 113 +/- 68 mg/2 hr P < 0.0001).
We conclude that one renal manifestation of insulin resistance may be low urinary ammonium and pH. This defect can result in increased risk of uric acid precipitation despite normouricosuria.
Previous studies have demonstrated that obesity can increase the risk of stone formation as well as recurrence rates of stone disease. Yet appropriate medical management can significantly decrease the risk of recurrent stone disease. Therefore, we analyzed our obese patient population, assessing the risk factors for stone formation and the impact of selective medical therapy on recurrent stone formation.
A retrospective chart review was performed to identify obese patients with stone disease from our Stone Center. Metabolic risk factors for stones were identified as well as patient response to medical therapy. A similar analysis was performed on a group of age and sex matched nonobese stone formers.
Of 1,021 patients 140 (14%) were identified as obese (body mass index greater than 30). Of these patients complete metabolic evaluations were available in 83 with an average followup of 2.3 years. The most common presenting metabolic abnormalities among these obese patients included gouty diathesis (54%), hypocitraturia (54%) and hyperuricosuria (43%), which presented at levels that were significantly higher than those of the nonobese stone formers (p <0.05). Stone analysis was available in 32 obese patients with 63% having uric acid calculi. After initiating treatment with selective medical therapy obese and nonobese patients demonstrated normalization of metabolic abnormalities, resulting in an average decrease in new stone formation from 1.75 to 0.15 new stones formed per patient per year in both groups.
Obesity, as a result of dietary indiscretion, probable purine gluttony and possible type II diabetes, appears to have a significant role in recurrent stone formation. Appropriate metabolic evaluation, institution of medical therapy and dietary recommendations to decrease animal protein intake can significantly improve the risk of recurrent stone formation in these often difficult to treat patients.
Larger body size may result in increased urinary excretion of calcium, oxalate, and uric acid, thereby increasing the risk for calcium-containing kidney stones. It is unclear if obesity increases the risk of stone formation, and it is not known if weight gain influences risk.
To determine if weight, weight gain, body mass index (BMI), and waist circumference are associated with kidney stone formation.
A prospective study of 3 large cohorts: the Health Professionals Follow-up Study (N = 45,988 men; age range at baseline, 40-75 years), the Nurses' Health Study I (N = 93,758 older women; age range at baseline, 34-59 years), and the Nurses' Health Study II (N = 101,877 younger women; age range at baseline, 27-44 years).
Incidence of symptomatic kidney stones.
We documented 4827 incident kidney stones over a combined 46 years of follow-up. After adjusting for age, dietary factors, fluid intake, and thiazide use, the relative risk (RR) for stone formation in men weighing more than 220 lb (100.0 kg) vs men less than 150 lb (68.2 kg) was 1.44 (95% confidence interval [CI], 1.11-1.86; P = .002 for trend). In older and younger women, RRs for these weight categories were 1.89 (95% CI, 1.52-2.36; P<.001 for trend) and 1.92 (95% CI, 1.59-2.31; P<.001 for trend), respectively. The RR in men who gained more than 35 lb (15.9 kg) since age 21 years vs men whose weight did not change was 1.39 (95% CI, 1.14-1.70; P = .001 for trend). Corresponding RRs for the same categories of weight gain since age 18 years in older and younger women were 1.70 (95% CI, 1.40-2.05; P<.001 for trend) and 1.82 (95% CI, 1.50-2.21; P<.001 for trend). Body mass index was associated with the risk of kidney stone formation: the RR for men with a BMI of 30 or greater vs those with a BMI of 21 to 22.9 was 1.33 (95% CI, 1.08-1.63; P<.001 for trend). Corresponding RRs for the same categories of BMI in older and younger women were 1.90 (95% CI, 1.61-2.25; P<.001 for trend) and 2.09 (95% CI, 1.77-2.48; P<.001 for trend). Waist circumference was also positively associated with risk in men (P = .002 for trend) and in older and younger women (P<.001 for trend for both).
Obesity and weight gain increase the risk of kidney stone formation. The magnitude of the increased risk may be greater in women than in men.
A larger body size has been shown to be associated with increased excretion of urinary lithogenic solutes, and an increased risk of nephrolithiasis has been reported in overweight patients. However, the type of stones produced in these subjects has not been ascertained. Based on a large series of calculi, we examined the relationship between body size and the composition of stones, in order to assess which type of stone is predominantly favoured by overweight. Among 18,845 consecutive calculi referred to our laboratory, 2,100 came from adults with recorded body height and weight. Excluding calculi from patients with diabetes mellitus, as well as struvite and cystine stones, the study material consisted of 1,931 calcium or uric acid calculi. All calculi were analysed by infrared spectroscopy and categorized according to their main component. Body mass index (BMI) values were stratified as normal BMI (2), overweight (BMI 25–29.9) or obese (BMI≥30). Overall, 27.1% of male and 19.6% of female stone formers were overweight, and 8.4 and 13.5% were obese, respectively. In males, the proportion of calcium stones was lower in overweight and obese groups than in normal BMI group, whereas the proportion of uric acid stones gradually increased with BMI, from 7.1% in normal BMI to 28.7% in obese subjects (PP=0.003). In addition, the proportion of uric acid stones markedly rose with age in both genders (P
Obesity is increasing in the American population in epidemic proportions. Weight reduction surgery results in sustained weight loss for morbidly obese individuals-a group of patients refractory to nonsurgical obesity treatment. Surgical indications were outlined in a National Institutes of Health (NIH) consensus conference published in 1991. Using the NIH criteria, we compared the socioeconomic characteristics of the population eligible for these operations to those receiving them.
The 2000 National Health Interview Survey database was examined to identify how many individuals in the American population were eligible for obesity operations. Socioeconomic characteristics for those individuals were then assessed. The Healthcare Cost and Utility Project and National Hospital Discharge Survey databases were queried to determine how many gastric bypass operations were performed and what the patient's socioeconomic characteristics were.
There are 5,324,123 people, or 2.8% of the American population, who are eligible for obesity surgery. Of these, a disproportionate number were black, poorly educated, or impoverished, and 38% rely on Medicare or Medicaid for their health insurance. Of the 28,590 gastric bypass operations performed in 2000, only 13% of patients used Medicare or Medicaid to pay for the operation. Fewer than expected operations were performed on blacks. Regional differences were observed with disproportionately more operations performed in the Northeast and fewer in the Midwest than would be predicted from the surgery-eligible population living in these regions.
A significant fraction of the American population could potentially benefit from obesity surgery. However, many of those individuals are black, poorly educated, and impoverished. Public assistance programs need to account for these patients. Centers performing bariatric operations need to accommodate the educational and financial constraints these patients have when planning long-term postoperative care.
Greater body mass index (BMI) is a risk factor for kidney stones. However, the relation between BMI and the urinary excretion of many lithogenic factors remains unclear.
We studied urine pH, urine volume, and 24-hour urinary excretion of calcium, oxalate, citrate, uric acid, sodium, magnesium, potassium, phosphate, and creatinine in stone-forming and non-stone-forming participants in the Health Professionals Follow-Up Study (599 stone-forming and 404 non-stone-forming men), Nurses' Health Study (888 stone-forming and 398 non-stone-forming older women), and Nurses' Health Study II (689 stone-forming and 295 non-stone-forming younger women). Each cohort was divided into quintiles of BMI. Tests of linear trend were conducted by 1-way analysis of variance. Linear regression models were adjusted for age, history of stone disease, dietary intake, and urinary factors.
Participants with greater BMIs excreted more urinary oxalate (P for trend <or= 0.04), uric acid (P < 0.001), sodium (P < 0.001), and phosphate (P < 0.001) than participants with lower BMIs. There was an inverse relation between BMI and urine pH (P <or= 0.02). Positive associations between BMI and urinary calcium excretion in men and stone-forming younger women (P <or= 0.02) did not persist after adjustment for urinary sodium and phosphate excretion. Because of differences in urinary volume and excretion of inhibitors such as citrate, we observed no relation between BMI and urinary supersaturation of calcium oxalate. Urinary supersaturation of uric acid increased with BMI (P <or= 0.01).
Positive associations between BMI and urinary calcium excretion likely are due to differences in animal protein and sodium intake. The greater incidence of kidney stones in the obese may be due to an increase in uric acid nephrolithiasis.
Obesity, weight gain, and the risk of kidney stones
- Taylor
Taylor EN, Stampfer MJ and Curhan GC: Obesity, weight gain, and the risk of kidney stones. JAMA 2005; 293: 455.
Metabolic risk factors and the impact of medical therapy on the management of nephrolithiasis in obese patients
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Ekeruo WO, Tan YH, Young MD, Dahm P, Maloney ME, Mathias BJ et al: Metabolic risk factors and the impact of medical therapy on the management of nephrolithiasis in obese patients. J Urol 2004; 172: 159.
Body size and risk of kidney stones
- Curhan
Curhan GC, Willett WC, Rimm EB, Speizer FE and Stampfer MJ: Body size and risk of kidney stones. J Am Soc Nephrol 1998; 9: 1645.
Urinary oxalate excretion increases with body size and decreases with increasing dietary calcium intake among healthy adults
- Lemann
Prevalence of the metabolic syndrome among US adults: findings from the third National Health and Nutrition Examination Survey
- Ford