[Show abstract][Hide abstract] ABSTRACT: Pathological calcification generally consists of the formation of solid deposits of hydroxyapatite (calcium phosphate) in soft tissues. Supersaturation is the thermodynamic driving force for crystallization, so it is believed that higher blood levels of calcium and phosphate increase the risk of cardiovascular calcification. However several factors can promote or inhibit the natural process of pathological calcification. This cross-sectional study evaluated the relationship between physiological levels of urinary phytate and heart valve calcification in a population of elderly out subjects. A population of 188 elderly subjects (mean age: 68 years) was studied. Valve calcification was measured by echocardiography. Phytate determination was performed from a urine sample and data on blood chemistry, end-systolic volume, concomitant diseases, cardiovascular risk factors, medication usage and food were obtained. The study population was classified in three tertiles according to level of urinary phytate: low (<0.610 μM), intermediate (0.61-1.21 μM), and high (>1.21 μM). Subjects with higher levels of urinary phytate had less mitral annulus calcification and were less likely to have diabetes and hypercholesterolemia. In the multivariate analysis, age, serum phosphorous, leukocytes total count and urinary phytate excretion appeared as independent factors predictive of presence of mitral annulus calcification. There was an inverse correlation between urinary phytate content and mitral annulus calcification in our population of elderly out subjects. These results suggest that consumption of phytate-rich foods may help to prevent cardiovascular calcification evolution.
PLoS ONE 08/2015; 10(8):e0136560. DOI:10.1371/journal.pone.0136560 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Improving knowledge about normal urine composition in children is important for early prevention of lithiasis. We describe urinary excretion values of calcium (Ca), magnesium (Mg), phosphate (P), citrate (Cit), uric acid (Ur), and oxalate (Ox) in healthy children with and without a family history of lithiasis, using a 12-h urine collection protocol.
Urine samples were obtained from 184 children (5-12 years): a spot sample collected in the afternoon, and a 12-h overnight sample. Solute/creatinine (Cr) and 12-h solute excretion was calculated.
Urinary excretion values of the studied solutes are presented as percentile values, separately for each type of sample. Due to age-related differences in the solute/creatinine ratios, except for Ca and Cit, results are described according to the child's age. The presence of excretion values related to an increased risk of lithiasis was more common in children with a family history.
We report data from urine samples collected by using a simplified collection protocol. The observed differences between children with and without a family history of lithiasis could justify that in population studies aimed at setting reference values, the former are excluded.
[Show abstract][Hide abstract] ABSTRACT: Background:
The prevalence of lithiasis is increasing at all ages. This study aimed to assess the crystallization risk in urine from healthy school children and to determine urinary parameters that are most associated with it.
Urine samples were obtained from 184 children aged 5-12 years: a spot sample collected in the afternoon, and a 12-h overnight sample. Information was obtained regarding family histories of lithiasis. Urine volume, pH, and biochemical parameters of stone risk were measured. Crystallization risk was defined by the presence of specific urine conditions that had previously been associated with stone formation in vitro.
Crystallization risk was observed in 15 % of spot urine samples and 54 % of 12-h samples. Metabolic abnormalities and a low urinary volume were more frequently detected in children with crystallization risk. Calcium excretion and calcium/citrate ratio were higher in children with a family history of lithiasis.
We observed a high prevalence of crystallization risk in urine, especially in children with a family history of the disease. Low urinary volume was the factor most associated with increased risk. Adequate fluid intake at an early age may be a simple and effective measure to reduce the incidence of nephrolithiasis.
[Show abstract][Hide abstract] ABSTRACT: Formation of calcium oxalate crystals, either as monohydrate or dihydrate, is apparently unrelated to urinary pH because the solubilities of these salts are practically unaltered at physiologic urinary pH values. However, a urinary pH <5.5 or >6.0 may induce uric acid or calcium phosphate crystals formation, respectively, which under appropriate conditions may induce the development of the calcium oxalate calculi. We assessed the relationship between the urinary pH and the formation of different types of calculi. A retrospective study in 1,478 patients was done. We determined the composition, macrostructure, and microstructure of the calculi and the urinary pH, 50.9% of calcium oxalate monohydrate unattached calculi were present in patients with urinary pH <5.5. We found that 34.1 and 41.5% of calcium oxalate dihydrate calculi were present in patients with urinary pH <5.5 and >6.0, respectively. Infectious calculi were found primarily in patients with urinary pH >6.0 (50.7%). Only calcium oxalate monohydrate papillary calculi were associated with urinary pH between 5.5 and 6.0 (43.1%). Urine of pH <5.5 shows an increased capacity to develop uric acid crystals, which can act as a heterogeneous nuclei of calcium oxalate crystals. In contrast, urine of pH >6.0 has an increased capacity to develop calcium phosphate crystals, which can act as a heterogeneous nuclei of calcium oxalate crystals. Oxalate monohydrate papillary calculi were associated to pH between 5.5 and 6.0 because the injured papilla acts as a heterogeneous nucleant. Consequently, measurement of urinary pH may be used to evaluate the lithogen risk of given urine.
Urological Research 05/2011; 40(1):41-6. DOI:10.1007/s00240-011-0389-3 · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Phytate as sodium salt has been used at high doses to treat stone-former patients with idiopathic hypercalciuria. The experimental and clinical hypocalciuric effects of dietary fiber have also been assigned to the presence of phytate as calcium-magnesium salt (phytin). As a consequence of the additional interest in phytate due to its capacity as crystallization inhibitor, now a study of the effects of potassium phytate on urinary calcium excretion is presented and compared with the effects caused by other phytate salts.
To study the effect of calcium-magnesium phytate, 36 Wistar rats (6 groups) were fed with a purified diet in which phytate was practically absent (4068.02 Reference Diet). Three groups were fed with increasing calcium amounts and with the same amount of phytin, each one corresponding to one control group. To study the effects of magnesium-potassium, sodium and potassium phytate salts, 48 Wistar rats (8 groups) were fed with UAR-A04 diet (a standard diet which contains 0.8% of phytin). Two control groups fed with low and high calcium amounts and 6 treated groups were formed. The effect of the dose of potassium phytate on urinary calcium was carried out using 2 additional groups of 6 Wistar rats each one fed with UAR-A04 diet and increasing amounts of potassium phytate.
No significant changes in urinary calcium were observed when phytin (calcium-magnesium phytate) was supplied. The urinary calcium was clearly reduced by the three phytate salts assayed (magnesium-potassium, sodium, potassium), but the most significant decrease was noticed when the potassium phytate salt was administered. Phytate administration, independently of the salt or dose used, did not significantly affect the urinary oxalate.
It can be clearly deduced that the effects of phytate on the urinary parameters, mainly calcium, fundamentally depend on the type of salt used. Thus, the most remarkable effects on urinary calcium reduction were caused by the potassium salt. Obviously, these findings must be confirmed in human studies.
Urologia Internationalis 02/2004; 72(3):237-43. DOI:10.1159/000077123 · 1.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The phytate urinary levels in a group of active calcium oxalate stone formers were studied and compared with those found in healthy people. Urinary phytate was significantly lower for stone formers. If deficit of the capacity to inhibit crystallization of calcium salts is considered an important factor related to calcium stone formation, the excretion of low phytate amounts could be an important risk factor in the development of this type of renal calculi. The influence of dietary phytate on urinary excretion was also studied. Clearly maintenance of a phytate-free diet significantly decreased the urinary excretion of phytate (about 50% after 36 h). This demonstrated the importance of dietary phytate in maintaining adequate urinary levels to permit effective crystallization inhibition of calcium salts and consequently preventing renal stone development.
Scandinavian Journal of Urology and Nephrology 07/2000; 34(3):162-4. · 1.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper presents the results of a test to globally determine the urinary risk factor of calcium stone formation in the evaluation of treatments using crystallization inhibitors, such as citrate and phytate.
Three groups of active calcium oxalate stone-formers have been selected. The lithogen urinary risk was determined using a specially designed disposable test before any medical treatment. After evaluation group I did not receive any treatment, group II was treated with potassium citrate and group III with a phytate-rich dietary complement. When 15 days had elapsed, the test to evaluate the risk of urinary calcium stone formation was applied again to the three groups. The main lithogenic biochemical parameters of each tested urine were also determined before and after treatment.
An important number of calcium oxalate stone-formers with high urinary risk factor (positive test) became negative after medical treatment (52% of the citrate-treated patients and 50% of the phytate-treated patients), but only 7% of the untreated patients (1 patient) showed a decrease in their urinary risk factor for calcium stones (negative test) after 15 days had elapsed. When the treatment was not effective, in an important number of cases, the urine contained high levels of calcium or showed pH values greater than 6.5.
From the obtained results it can be concluded that the test is useful to evaluate the efficacy of a given renal lithiasis medical treatment, and also the efficacy of the treatment of calcium oxalate renal lithiasis using crystallization inhibitors, such as citrate and phytate, in an important number of cases.
Archivos españoles de urología 05/1999; 52(3):305-10. · 0.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A simple test to evaluate the capacity of a urine to crystallize calcium salts is presented. The test is based on the fact that if a non-protected non-renewed surface remains in contact with a urine, sooner or later the contained supersaturated substances crystallize on it. Thus, by using an adequate surface, it is possible to derive a period within which a normal urine does not crystallize whereas a lithogenic urine induces the growth of calcium salts. The test was applied to urines of oxalocalcic stone-formers and healthy people and showed an excellent discrimination between clearly abnormal and healthy urines. Semiologic analysis of the data is also included.