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Effects of Water Consumption on Kidney Function and Excretion
Abstract
Water homeostasis depends on fluid intake and maintenance of body water balance by adjustment of renal excretion under the control of arginine vasopressin hormone. The human kidney manages more efficiently fluid excess than fluid deficit. As a result, no overhydration is observed in healthy individuals drinking a large amount of fluid, whereas a mild hydration deficit is not uncommon in small-fluid-volume (SFV) drinkers. Small-fluid-volume intake does not alter renal function but is associated with an increased risk of renal lithiasis and urinary tract infection. In that case, increasing fluid intake prevents recurrence. The benefit of increasing fluid intake in healthy SFV drinkers had never been studied until now. Two recent studies from Danone Research indicate that increasing water intake in such people leads to a significant decrease of the risk of renal stone disease (assessed by measuring Tiselius' crystallization risk index). Because renal lithiasis and urinary tract infection prevalence are quite high in western countries, this preliminary observation supports the interest of an approach based on primary prevention using voluntary increase in water-based fluid consumption in SFV drinkers. Complementary studies are required to determine other clinical impacts of SFV intake and to evaluate the benefits of increasing fluid intake
... L/d) and 24-h TFI (0.6-2.3 L/d), and U800 may or may not represent impending dehydration. However, U800 is meaningful in terms of kidney health, in that nephrologists 1) recognize that a low daily water intake increases the risk of urolithiasis and chronic kidney disease [25,26], and 2) promote increased 24-h TFI as the simplest and most effective means of reducing the risk of renal disease [23,[27][28][29]. Their rationale recognizes that underconsumption of water results in urinary supersaturation, the driving force for crystallization and kidney stone formation [30]. ...
... Recognizing that chronically concentrated urine imparts negative health outcomes [20,[25][26][27][28][29][30], the U800 laboratory method determines the point at which 24-h water intake is inadequate, utilizing measurements of osmolality in 24-h urine samples [10][11][12][13][14][15]. This straightforward method could be applied to demographic groups with very different lifestyles including men or women, children, pregnant women, residents of a geographic region, populations who consume specialized or modified diets (e.g., low carbohydrate, high protein, low salt), and individuals who chronically lose a large volume of sweat each day (e.g., laborers, soldiers, athletes, and desert dwellers). ...
... Although there are several studies analyzing the effects of different food products, diet types, or alcohol consumption, little is known about the impact of water intake on hyperuricemia [10,11]. sUA is mainly excreted through the kidneys (70%) and normal kidney function depends on optimal hydration status [12,13]. There is also evidence that dehydration caused by exercise-induced excessive sweating or sauna bathing increases sUA levels [14]. ...
Background:
Hyperuricemia is well-known as an independent risk factor for the development of hypertension, metabolic syndrome, and cardiovascular disease. Water is essential to most bodily functions, and its consumption rates appear to decline with age. The aim was to evaluate the influence of water intake on early vascular aging in metabolic middle-aged patients with hyperuricemia.
Materials and methods:
The study included 241 men aged 40-55 years and 420 women aged 50-65 years from the Lithuanian High Cardiovascular Risk (LitHiR) primary prevention program. Anthropometric characteristics, blood pressure, laboratory testing, and the specialized nutrition profile questionnaire were evaluated. Carotid-femoral pulse wave velocity (cfPWV), assessed using applanation tonometry, was evaluated as an early vascular aging parameter in patients with hyperuricemia and with normal serum uric acid (sUA) levels.
Results:
72.6% of men and 83.1% of women drink insufficient amounts of water (less than 1.5 L per day). However, our results showed statistically significant relationships only among a group of women. The women in the hyperuricemic group had a higher cfPWV than women with normal sUA levels. In hyperuricemic women, drinking less than 0.5 L per day in combination with other risk factors, such as age, increasing fasting glucose, and systolic blood pressure, was statistically significantly associated with an increased cfPWV (R2 = 0.45, Adj. R2 = 0.42, p < 0.001).
Conclusion:
Drinking an insufficient amount of water daily is associated with increased arterial stiffness and has a negative effect on vascular health in metabolic women with hyperuricemia.
... Sufficient amount of water consumption can also lead to mood, feeling, and calm in a positive way [5]. In the long run, inadequate water consumption is proven to be influential in increasing the risk of non-communicable diseases such as urinary tract infection and kidney stones [6,7]. Pan et al. and Muckelbauer et al. reported that water consumption was a potential protective factor of obesity [8,9]. ...
Objectives
There are many water types available on the market. They are widely known in public with health claims. The questions are, are those claims are scientifically proven or those are just testimonies from the consumers or overclaimed by the producers. This study aims to systematically review evidences on the health effects of alkaline, oxygenated, and demineralized water in comparison with mineral water among healthy population.
Contents
Data were obtained from databases PubMed, Cochrane, Scopus, EBSCO, dan Science Direct since January 2000 until July 2022. There were 10 eligible articles, consisted of two articles on alkaline, four articles on oxygenated, and four articles on demineralized water, that furtherly being analyzed.
Summary
Compared to consumption of mineral water, consumption of alkaline and oxygenated water did not show any significant difference on gut microbiota, urine pH, blood parameter, or fitness parameter. While, consumption of demineralized water in the long term resulted in lower quality of certain nutrient intake.
Outlook
Recent evidences do not prove any additional health effects of alkaline, oxygenated, or demineralized water compared to mineral water. In contrast, demineralized water consumption in the long run was proven to lead to adverse effect.
... For these reasons, excessive salt intake must be avoided in children with a CSK, remembering that table salt only represents approximately 10% of the daily intake, the greatest amount being contained in processed foods [99]. As in children with two kidneys, normal hydration should be guaranteed at all times, and in particular during sport activities, as a small-volume fluid intake, although not altering kidney function, is associated with an increased risk of urolithiasis and UTI [100]. ...
Background:
In recent years, several studies have been published on the prognosis of children with congenital solitary kidney (CSK), with controversial results, and a worldwide consensus on management and follow-up is lacking. In this consensus statement, the Italian Society of Pediatric Nephrology summarizes the current knowledge on CSK and presents recommendations for its management, including diagnostic approach, nutritional and lifestyle habits, and follow-up. We recommend that any antenatal suspicion/diagnosis of CSK be confirmed by neonatal ultrasound (US), avoiding the routine use of further imaging if no other anomalies of kidney/urinary tract are detected. A CSK without additional abnormalities is expected to undergo compensatory enlargement, which should be assessed by US. We recommend that urinalysis, but not blood tests or genetic analysis, be routinely performed at diagnosis in infants and children showing compensatory enlargement of the CSK. Extrarenal malformations should be searched for, particularly genital tract malformations in females. An excessive protein and salt intake should be avoided, while sport participation should not be restricted. We recommend a lifelong follow-up, which should be tailored on risk stratification, as follows: low risk: CSK with compensatory enlargement, medium risk: CSK without compensatory enlargement and/or additional CAKUT, and high risk: decreased GFR and/or proteinuria, and/or hypertension. We recommend that in children at low-risk periodic US, urinalysis and BP measurement be performed; in those at medium risk, we recommend that serum creatinine also be measured; in high-risk children, the schedule has to be tailored according to kidney function and clinical data.
... The evaluation of hydration status in the general population in free-living and/or under special conditions such as in disease or in the work environment is of unequivocal importance for public health. This is because dehydration is linked with reduced physical and cognitive performance [1] or disease [2,3]. ...
Hydration status is linked with health, wellness, and performance. We evaluated hydration status, water intake, and urine output for seven consecutive days in healthy adults. Volunteers living in Spain, Germany, or Greece (n = 573, 39 ± 12 years (51.1% males), 25.0 ± 4.6 kg/m2 BMI) participated in an eight-day study protocol. Total water intake was estimated from seven-day food and drink diaries. Hydration status was measured in urine samples collected over 24 h for seven days and in blood samples collected in fasting state on the mornings of days 1 and 8. Total daily water intake was 2.75 ± 1.01 L, water from beverages 2.10 ± 0.91 L, water from foods 0.66 ± 0.29 L. Urine parameters were: 24 h volume 1.65 ± 0.70 L, 24 h osmolality 631 ± 221 mOsmol/kg Η2Ο, 24 h specific gravity 1.017 ± 0.005, 24 h excretion of sodium 166.9 ± 54.7 mEq, 24 h excretion of potassium 72.4 ± 24.6 mEq, color chart 4.2 ± 1.4. Predictors for urine osmolality were age, country, gender, and BMI. Blood indices were: haemoglobin concentration 14.7 ± 1.7 g/dL, hematocrit 43% ± 4% and serum osmolality 294 ± 9 mOsmol/kg Η2Ο. Daily water intake was higher in summer (2.8 ± 1.02 L) than in winter (2.6 ± 0.98 L) (p = 0.019). Water intake was associated negatively with urine specific gravity, urine color, and urine sodium and potassium concentrations (p < 0.01). Applying urine osmolality cut-offs, approximately 60% of participants were euhydrated and 20% hyperhydrated or dehydrated. Most participants were euhydrated, but a substantial number of people (40%) deviated from a normal hydration level.
... The evaluation of hydration status in the general population in free-living and/or under special conditions such as in disease or in the work environment is of unequivocal importance for public health. This is because dehydration is linked with reduced physical and cognitive performance [1] or disease [2,3]. ...
Hydration status is linked with health, wellness, and performance. We evaluated hydration status, water intake, and urine output for seven consecutive days in healthy adults. Volunteers living in Spain, Germany, or Greece (n = 573, 39 ± 12 years (51.1% males), 25.0 ± 4.6 kg/m² BMI) participated in an eight-day study protocol. Total water intake was estimated from seven-day food and drink diaries. Hydration status was measured in urine samples collected over 24 h for seven days and in blood samples collected in fasting state on the mornings of days 1 and 8. Total daily water intake was 2.75 ± 1.01 L, water from beverages 2.10 ± 0.91 L, water from foods 0.66 ± 0.29 L. Urine parameters were: 24 h volume 1.65 ± 0.70 L, 24 h osmolality 631 ± 221 mOsmol/kg Η₂Ο, 24 h specific gravity 1.017 ± 0.005, 24 h excretion of sodium 166.9 ± 54.7 mEq, 24 h excretion of potassium 72.4 ± 24.6 mEq, color chart 4.2 ± 1.4. Predictors for urine osmolality were age, country, gender, and BMI. Blood indices were: haemoglobin concentration 14.7 ± 1.7 g/dL, hematocrit 43% ± 4% and serum osmolality 294 ± 9 mOsmol/kg Η₂Ο. Daily water intake was higher in summer (2.8 ± 1.02 L) than in winter (2.6 ± 0.98 L) (p = 0.019). Water intake was associated negatively with urine specific gravity, urine color, and urine sodium and potassium concentrations (p < 0.01). Applying urine osmolality cut-offs, approximately 60% of participants were euhydrated and 20% hyperhydrated or dehydrated. Most participants were euhydrated, but a substantial number of people (40%) deviated from a normal hydration level.
... Por otro lado, no es importante dejar de lado las calorías aportadas por las bebidas alcohólicas. Claramente, no hay que tomar agua sólo cuando se tiene sed, la sed aparece cuando ya existe deshidratación 25,26 . La sed se desencadena por mecanismos fisiológicos (incremento de la osmolaridad plasmática y reducción del volumen plasmático) y perceptivos (sabor, color y temperatura de las bebidas). ...
Introducción. El agua es fundamental para la vida; sin embargo, la aparición de información errónea generó dudas en la población.Objetivo. Determinar el porcentaje de acuerdo y de influencia sobre el consumo de líquidos de creencias erróneas vinculadas a la hidratación en la población argentina. Material y métodos. Estudio descriptivo, prospectivo, observacional y transversal. Se realizaron 1014 entrevistas directas, domiciliarias, con una cobertura nacional a individuos de ambos sexos >18 años de edad. Se aplicó un muestreo probabilístico, polietápico y estratificado.Resultados. El 80% (IC 95%:75,8%-84,2%) de la población entrevistada estuvo de acuerdo con la creencia que"para cuidar el corazón, hay que tomar agua baja en sodio". Fue más arraigada en: mujeres (p=0,0169), > 65 años (p=0,005), mayor nivel educacional (p=0,026) y nivel socioeconómico medio (p=0,019), Ciudad Autónoma de Buenos Aires (p=0,005) y Gran Buenos Aires (p=0,000). La influencia de esta creencia en el consumo de líquidos fue del 77% (IC 95%: 72,8%-81,2%). El 62% (IC 95%: 57,8%-66,2%) estuvo de acuerdo con la creencia "para cuidar que los chicos no engorden, hay que fijarse más en la comida que en la bebida", principalmente en el nivel educacional (p=0,015) y socioeconómico más bajo (p=0,014). La influencia en la ingesta de líquidos fue del 74% (IC 95%: 69,8%-78,2%). Mientras que el grado de acuerdo fue menor en: "cualquier bebida hidrata por igual, no es necesario tomar agua" (33%, IC 95%: 28,8%-37,2%), "hay que tomar agua sólo cuando se tiene sed" (31%, IC 95%: 26,8%-35,2%), "tomar agua durante las comidas dificulta la digestión" (27%, IC 95%: 22,8%-31,2%); la influencia sobre la ingesta de líquidos fue alta: 70% (IC 95%: 65,8%-74,2%), 65% (IC 95%: 60,8%-69,2%) y 60% (IC 95%: 55,8%-64,2%) respectivamente.Conclusión. Se observó alto grado de acuerdo sólo en 2 creencias, aunque las 5 tuvieron influencia en la ingesta de líquidos.
... 17 Consequently, it is fitting that our current water recommendations outlined by the Institute of Medicine are described as ''adequate intakes'' 18 because, given the vast flexibility of renal water reabsorptive capabilities, 3700 mL/d for men and 2700 mL/d for women are enough to enable all cellular processes that require water and eliminate urinary wastes safely. 15 It is important to state that these recommendations have been based upon ''median intakes,'' which enable the maintenance of serum osmolality. Although serum osmolality is sensitive to exercise-induced dehydration, these guidelines fail to take into account the potential negative consequences of long-term low or high fluid intake compensation. ...
Normal human water intake spans a large range owing to the body's ability to excrete large volumes of water in times of excess and conserve in times of scarcity. Recently, chronic intakes of either large volumes (HIGH) or small volumes (LOW) of water have been investigated. Adaptations within the renal regulation of water through the secretion and reabsorptive actions of the hormone arginine vasopressin and the thirst mechanism have been observed to differentiate these 2 groups during normal living. Increases or decreases in daily fluid intake in LOW and HIGH resulted in appropriate arginine vasopressin and perception of thirst changes, which enabled fluid balance in both of these populations. However, future research should establish if the chronic adaptive mechanisms, by which fluid is regulated have long-termnegative outcomes. Copyright
... From the biochemical urine analyses, the Tiselius Crystallization Risk Index (CRI) was calculated (18) . The Tiselius CRI is useful in evaluating the risk of recurrent kidney stone formation, and takes into account the total volume of urine produced as well as the excretion of solute elements that increase (Ca and oxalate) or decrease (Mg and citrate) the risk of calcium oxalate stone formation (19) . ...
Little is known about the impact of habitual fluid intake on physiology. Specifically, biomarkers of hydration status and body water regulation have not been adequately explored in adults who consume different fluid volumes in everyday conditions, without prolonged exercise or environmental exposure. The purpose of the present study was to compare adults with habitually different fluid intakes with respect to biomarkers implicated in the assessment of hydration status, the regulation of total body water and the risk of kidney pathologies. In the present cross-sectional study, seventy-one adults (thirty-two men, thirty-nine women, age 25-40 years) were classified according to daily fluid intake: thirty-nine low drinkers (LD; ≤ 1·2 litres/d) and thirty-two high drinkers (HD; 2-4 litres/d). During four consecutive days, urinary parameters (first morning urine (FMU) on day 1 and subsequent 24 h urine (24hU) collections), blood parameters, and food and beverage intake were assessed. ANOVA and non-parametric comparisons revealed significant differences between the LD and HD groups in 24hU volume (1·0 (se 0·1) v. 2·4 (se 0·1) litres), specific gravity (median 1·023 v. 1·010), osmolality (767 (se 27) v. 371 (se 33) mOsm/kg) and colour (3·1 (se 0·2) v. 1·8 (se 0·2)). Similarly, in the FMU, the LD group produced a smaller amount of more concentrated urine. Plasma cortisol, creatinine and arginine vasopressin concentrations were significantly higher among the LD. Plasma osmolality was similar between the groups, suggesting physiological adaptations to preserve plasma osmolality despite low fluid intake. The long-term impact of adaptations to preserve plasma osmolality must be examined, particularly in the context of renal health.
In this paper I estimate the magnitude of association between water/sanitation infrastructure and health/well-being for First Nations individuals living on reserve in Canada in 2002/3, 2008/10 and 2015/6. I find that access to an indoor water supply is associated with an 80% reduction in the odds of reporting depression. In-home sanitation is associated with a reduction in depression, gastrointestinal illness and kidney problems. These results suggest that large health benefits can be achieved through increased infrastructure investment in First Nations across Canada. Existing houses should also be retrofitted to ensure all homes have access to running water/sanitation.
Physical fitness development programs for elementary schools received less attention in particular .
Report the results of national research , among others, the fitness level of our society mean less . Data
of SDI( Sport Development Index) 2006 states that approximately 37.40 % in the category once ;
43.90 % less ; 13.55 % moderate ; 4.07 % good , and only 1.08 % either once ( Mutohir , Toho Cholik
and Ali infallible , 2007 : 111 )26 , it is still difficult to find the presence of a teacher Physical
education around us were competent and successfully manage their subject , so that students love ,
respect and sincere in following the learning process and to induce an active and healthy lifestyle in
everyday life ( Komnas Penjasor , 2007).12 So that problems can be discussed needed monitoring and
efficiency , especially strength training program on physical fitness in elementary school ? The
purpose of this study is to analyze the need for the monitoring of information about strength
development program on primary school children in physical fitness teaching materials.. Review of
the literature on this issue resulted in the need for information and monitoring strength training
programs on a regular basis and special . This is in line wscott and avery29 opinion and also Keith
Scott Cinea22 . The importance of determining the form of exercise , intensity , sets , reps are in
accordance with the characteristics of children of primary school age ( 7-12 years ) . Able whether
Teacher Physical Education accommodates this strength building exercises by an average of 30
students each class? This needs with the technology of computer information systems to help monitor
and strength training program with the appropriate composition . This study resulted in the idea of
developing software for strength training that can be accessed by teachers and students that are widely
useful for the user .
The urinary tract plays an important role in our daily health in removing toxins, in ensuring that body absorbs the adequate amount of water, keeping the body hydrated to help flush out and eradicate bacteria from the urinary tract. This manuscript aims to find the effect of low water intake and the effect of excessive consuming of fizzy drink on producing urinary tract infection. 200 individuals who recommended by physicians to general urine examination in Shaqlawa Hospital-Kurdistan region / Iraq were investigated; the analysis included three areas of concern: the exact amount of water consumption each day by the patient, the exact amount of fizzy drink consumption by the patient and the laboratory report for each patient. Lab reports show the great difference between patients who used to consume sufficient amount of water daily and patient who don't retain drinking sufficient amount of water daily. Lab report shows that patient who accustomed consume the fizzy drink in excessive amount are having severe urinary tract infection representative by bacteria, pus cell, RBC and epithelial cell, a patient who don't consume fizzy drink or patient who not use to consume fizzy drink were less infected.
Introduction. Water is essential for life, but the emergence of misinformation created doubts in the population. Objective. To determine the percentage of agreement and influence on fluid intake of misconceptions related to hydration argentine population. Material and methods. In this prospective, observational and transversal study, we conducted 1014 direct interviews, home, with a national coverage to individuals of both genders> 18 years of age. We applied a probabilistic sampling, multistage and stratified. Results. The 80% (95% CI: 75.8%-84.2%) of those interviewed agreed with the belief that "to care your heart, take water low in sodium". It was more prevalent in: women (p=0.0169), >65 years (p=0.005), higher educational level (p=0.026) and middle socioeconomic status (p=0.019), Buenos Aires city (p=0.005) and Gran Buenos Aires (p=0.000). The influence of this belief in fluid intake was 77% (95% CI: 72.8%-81.2%). The 62% (95% CI: 57.8%-66.2%) agreed with the belief "to take care that the kids do not get fat, you have to focus more on the food than the drink", mainly at the level education (p=0.015) and lower socioeconomic (p=0.014). The influence on fluid intake was 74% (95% CI: 69.8%-78.2%). While the level of agreement was lower in "any beverage hydrates alike, do not need to drink water" (33%, 95% CI: 28.8%-37.2%), "you have to drink water only when thirst" (31%, 95% CI: 26.8%-35.2%), "drink water during meals hampers digestion" (27%, 95% CI: 22.8%-31.2%), the influence of fluid intake was high: 70% (95% CI: 65.8%-74.2%), 65% (95% CI: 60.8%-69.2%) and 60% (95% CI: 55.8%-64.2%), respectively. Conclusion. There was high agreement in only two beliefs, although five had an influence on fluid intake.
Background/objectives:
This investigation evaluated 12 hydration biomarkers, to determine which represent 24-h whole-body water balance (that is, measured as water retention or clearance (WR-C) by the kidneys).
Subjects/methods:
Healthy males (n=59; body mass, 75.1±7.9 kg; height, 178±6 cm; age, 22±3 years; body mass index, 23.9±2.4 kg/m(2)) met with a registered dietitian each morning (days 1-11) to optimize completeness and accuracy of food and fluid records, then went about ordinary daily activities. These men visited the laboratory for blood samples and collected all urine produced on days 1, 3, 6, 9 and 12. The reference standard (WR-C) was calculated using 24-h urine volume, 24-h urine osmolality, and serum osmolality (single morning venous sample).
Results:
Statistical regression analyses indicated that, among the 12 hydration biomarkers, only 24-h urine osmolality (r(2)=0.60, P<0.0001) and 24-h urine specific gravity (r(2)=0.52, P<0.0001) strongly predicted WR-C. The 24-h fluid intake, 24-h body mass change, 24-h urine color and 24-h urine volume were weak (P>0.05) predictors of WR-C, similar to serum osmolality and other single measurements (range of r(2) values, 0.19-0.0001).
Conclusions:
These observations of healthy, active young men demonstrate that WR-C is strongly related to the 24-h concentration of urine, which in turn reflects the excretion of total solids in the diet. Although morning urine assessments provided information about a single time point, 24-h urine osmolality and 24-h urine specific gravity were the best predictors of 24-h body water balance.
The hypothesis that the incidence of calcium stone disease is related to the consumption of animal protein has been examined. Within the male population, recurrent idiopathic stone formers consumed more animal protein than did normal subjects. Single stone formers had animal protein intakes intermediate between those of normal men and those of recurrent stone formers. A high animal protein intake caused a significant increase in the urinary excretion of calcium, oxalate and uric acid, 3 of the 6 main urinary risk factors for calcium stone formation. The overall relative probability of forming stones, calculated from the combination of the 6 main urinary risk factors, was markedly increased by a high animal protein diet. Conversely, a low animal protein intake, such as taken by vegetarians, was associated with a low excretion of calcium, oxalate and uric acid and a low relative probability of forming stones.
The risk of calcium crystallization (CaOx-CR) in urine was analyzed by means of crystal counting following standardized addition of oxalate. CaOx-CR was determined in 24 h urine samples from 21 stone formers and 26 normal subjects following dilution of urine to a creatinine concentration of 5 mumol per ml. The mean (+/- SD) CaOx-CR was in stone formers 1.42 +/- 0.57 and in normal subjects 1.29 +/- 0.40. CaOx-CR was also analyzed in 16 fresh urine samples diluted to 80 per cent of the original concentration whereby values between 0.36 and 3.6 were recorded. There was a good correlation between CaOx-CR and estimates of the ion-activity product of CaOx, both in urine diluted to 5 mumol of creatinine per ml and in 80 per cent diluted urine. It ist suggested that the method described is of value for evaluation and follow up of patients with CaOx urolithiasis.
Using the ambulatory protocol previously described, 241 patients with nephrolithiasis were evaluated. They could be categorized into 10 groups from the results obtained. Absorptive hypercalciuria type I (87 per cent male) comprised 24.5 per cent and was characterized by normocalcemia, normal fasting urinary calcium (less than 0.11 mg/100 ml glomerular filtration), an exaggerated urinary calcium following an oral calcium load (greater than 0.20 mg/mg creatinine), normal urinary cyclic adenosine monophosphate (AMP) (less than 5.4 nmol/100 ml glomerular filtration) and serum parathyroid hormone (PTH), and hypercalciuria (greater than 200 mg/day during a calcium- and sodium-restricted diet). Absorptive hypercalciuria type II (50 per cent male) accounted for 29.8 per cent; its biochemical features were the same as those for absorptive hypercalciuria type I, except for normocalciuria during a restricted diet and low urine volume (1.42 +/- 0.55 SD liter/day). Renal hypercalciuria (56 per cent male), disclosed in 8.3 per cent, was represented by normocalcemia and high values for fasting urinary calcium (0.160 +/- 0.054 mg/100 ml glomerular filtration), urinary cyclic AMP (6.80 +/- 2.10 nmol/100 ml glomerular filtration) and serum PTH. Primary hyperparathyroidism (57 per cent female), accounted for 5.8 per cent, typically included hypercalcemia, hypophosphatemia, hypercalciuria and high urinary cyclic AMP. Hyperuricosuric calcium urolithiasis (100 per cent male) comprised 8.7 per cent, and was characterized by hyperuricosuria (776 +/- 164 mg/day) and urinary pH exceeding pK for uric acid (5.91 +/- 0.33). In enteric hyperoxaluria (60 per cent female), encountered in 2.1 per cent of cases, urinary oxalate was increased (6.29 +/- 13.2 mg/day). Noncalcium-containing stones were found in 2.1 per cent of the patients with uric acid lithiasis (100 per cent male) and in another 2.1 per cent of the patients with infection lithiasis (60 per cent female). These conditions were typified by low urinary pH (5.29 +/- 0.12) and high urinary pH (6.69 +/- 1.16), respectively. Renal tubular acidosis was found in one patient (male, 0.4 per cent). In 10.8 per cent of the patients (81 per cent male), no metabolic abnormality could be found, although urine volume was low (1.41 +/- 0.51 liter/day). Hypercalciuria could not be differentiated between absorptive hypercalciuria and renal hypercalciuria in 5.4 per cent of the patients. Thus, this ambulatory protocol disclosed a physiologic disturbance in nearly 90 per cent of the cases and provided a definitive diagnosis in 95 per cent of the patients.
Constituents of 6-hour (0900-1500 hours) urine collected during rest and exercise have been compared among 3 groups of male volunteers. Groups 1 and 2 (GI, GII) were normal controls residing in an urban area (n = 10) and rural villages (n = 9), respectively, and group 3 (GIII) consisted of 10 renal stone formers from the same location as GII. Exercise was performed by cycling on an electronic bicycle with three 150-watt loads and the duration of each load was 20 minutes. Collected usine was analyzed for volume, pH, PI (permissible increment) in oxalate, creatinine, calcium, sodium, potassium, phosphorus, oxalate, uric acid and citrate. The results showed that most urinary excretions during both rest and exercise periods were similar among the 3 groups. Only the following values were significantly different, ie in the rest period, calcium of GIII < GII (p < .01) and potassium of GII < GI (p < .05); in the exercise period, potassium of GIII < GI (p < .02) and phosphorus of GIII < GII (p < .03). In comparison between the rest and exercise periods within each group, the decreased total excretions during exercise were creatinine of GI (p < .05) and GIII (p < .05), calcium of GII (p < .05) and phosphorus of GIII (p < .05); only calcium of GIII (p < .05) was increased. However, when the concentration of each constituent was taken into consideration, most constituents increased in concentration during the exercise period due to the fall in urinary volume. Furthermore, during exercise both pH and PI in oxalate of urine decreased significantly. Thus the results of our study suggested that though most total urinary excretion patterns were similar between the rest and exercise periods, the risk of stone formation in the urinary tract during exercise could be enhanced. The enhanced risk is likely due to 3 main factors, ie (1) decrease in urinary volume, (2) increased propensity for crystallization of calcium oxalate (PI in oxalate decreased) and (3) decrease in urinary pH which will directly cause an increase in saturation level of uric acid. This increased risk of stone formation was consistently observed in all three groups of subjects.
A high fluid intake is the oldest existing treatment for kidney stones, and, up until a few decades ago, it was the only preventive measure at the physician's disposal for stone recurrences.
Using the data available in literature and partly unpublished personal research, we examine the role of urine volume as a stone risk factor, its impact on calcium crystallization mechanisms and its real importance as a means of prevention.
To sum up, the most important findings are: (1) a low urine volume must be considered as a real risk factor, both as regards the onset of renal calculi and stone relapses; (2) an increase in urine volume induced by a high water intake produces favourable effects on the crystallization of calcium oxalate and does not reduce the activity of natural inhibitors; (3) a sufficiently high intake of water and probably other fluids such as coffee, tea, beer and wine has a preventive effect on nephrolithiasis and its recurrence, and (4) the role of fruit juice is still to be defined.
A high intake of fluids, especially water, is still the most powerful and certainly the most economical means of prevention of nephrolithiasis, and it is often not used to advantage by stone formers.