Calcium oxalate urolithiasis in children: urinary promoters/inhibitors and role of their ratios.

Diagnostic criteria for determination of inclination towards idiopathic calcium oxalate (CaOx) urolithiasis based on biochemical urine parameters are not sufficiently well defined in children. The aim of this study was to determine the risk of CaOx urolithiasis in children from concentrations of calcium, oxalate, citrate, and glycosaminoglycans in urine and their ratios, all standardized in respect to creatinine. We collected and analyzed 24-h urine samples of children with CaOx urolithiasis (n = 61) and compared with urine samples of matched control group of healthy children (n = 25). The study has showed that all stone formers have higher excretion of calcium (mmol/mmol creatinine), calcium/citrate (mol/mmol), and oxalate/(citrate × glycosaminoglycans) ratio (mol Ox × mol cr)/(mol Cit × g GAGs). ROC analysis of these variables gave criteria (>0.28, >1.07, and >0.08, respectively) for distinguishing stone formers from healthy children. Biochemical urine parameters and their ratios (calcium, calcium citrate, and oxalate/(citrate × glycosaminoglycans) enable one to discriminate idiopathic calcium oxalate stone formers from healthy children. Oxalate/(citrate × glycosaminoglycans) ratio per se can serve as an independent risk for stone formation. CONCLUSION: Using biochemical urine parameters and their ratios such as calcium, calcium/citrate, and oxalate/(citrate × glycosaminoglycans) enables one to determine diagnostic criteria towards idiopathic calcium oxalate urolithiasis in children. What is known: • The role of urine calcium as a promoter in calcium oxalate urolithiasis is well established. • Seldom used calcium/citrate ratio is acknowledged as a risk factor for calcium/oxalate urolithiasis. What is new: • The values of calcium and citrate in clinically and genetically proven idiopathic calcium oxalate urolithiasis make calcium/citrate ratio useful for diagnostic purposes in such stone formers. • Rarely used calcium independent oxalate/(citrate x glycosaminoglycans) ratio serves as the second best high specificity marker for idiopathic calcium oxalate urolithiasis.

Are patients with lichen planus really prone to urolithiasis? Lichen planus and urolithiasis.

PURPOSE: to investigate whether patients with lichen planus (LP) are really prone to urolithiasis or not. PATIENTS AND METHODS: We performed a prospective analysis of 40 patients diagnosed with lichen planus (LP) (group I), and 40 volunteers did not have LP before (group II). Participants were all checked for urolithiasis by radiological investigations. Blood samples were analyzed for biochemistry parameters including calcium and uric acid. 24-h urine samples were analyzed to investigate oxalate, citrate calcium, uric acid, magnesium, sodium and creatinine. RESULTS: Men/women ratio and mean age were similar between group I and II (p>0.05). A presence or history of urolithiasis was detected in 8 (20%) and 2 (%5) patients in group I and II, respectively (p<0.05). Hypocitraturia was the most common anomaly with 35% (n:14) in group I. The rate of hypocitraturia in group II was 12.5% (n:5) and the difference was statistically significantly different (p=0.036). In group I, hyperuricosuria and hyperoxaluria followed with rates of 27.5% (n:11) and 25% (n:10), respectively. The rate of hyperuricosuria and hyperoxaluria were both 5% (n:2) in group II and the differences were significant (p<0.05). Hyperuricemia was another importante finding in the patients with LP. It was detected in 13 (32.5%) patients in group I and in 1 (2.5%) participant in group II (p=0.001). CONCLUSION: According to our results, metabolic disorders of urolithiasis were highly detected in the patients with LP. However, similar to the etiology of LP, the exact reasons for these metabolic abnormalities in LP remain a mystery.

Are patients with lichen planus really prone to urolithiasis? Lichen planus and urolithiasis

ABSTRACT Purpose to investigate whether patients with lichen planus (LP) are really prone to urolithiasis or not. Patients and Methods We performed a prospective analysis of 40 patients diagnosed with lichen planus (LP) (group I), and 40 volunteers did not have LP before (group II). Participants were all checked for urolithiasis by radiological investigations. Blood samples were analyzed for biochemistry parameters including calcium and uric acid. 24-h urine samples were analyzed to investigate oxalate, citrate calcium, uric acid, magnesium, sodium and creatinine. Results Men/women ratio and mean age were similar between group I and II (p>0.05). A presence or history of urolithiasis was detected in 8 (20%) and 2 (%5) patients in group I and II, respectively (p<0.05). Hypocitraturia was the most common anomaly with 35% (n:14) in group I. The rate of hypocitraturia in group II was 12.5% (n:5) and the difference was statistically significantly different (p=0.036). In group I, hyperuricosuria and hyperoxaluria followed with rates of 27.5% (n:11) and 25% (n:10), respectively. The rate of hyperuricosuria and hyperoxaluria were both 5% (n:2) in group II and the differences were significant (p<0.05). Hyperuricemia was another important finding in the patients with LP. It was detected in 13 (32.5%) patients in group I and in 1 (2.5%) participant in group II (p=0.001). Conclusion According to our results, metabolic disorders of urolithiasis were highly detected in the patients with LP. However, similar to the etiology of LP, the exact reasons for these metabolic abnormalities in LP remain a mystery.

Effect of dietary mineral sources and oil content on calcium utilization and kidney calcification in female Fischer rats fed low-protein diets.

We studied the effects of dietary mineral source and oil intake on kidney calcification in 4-wk-old female Fischer rats after consuming the AIN-76 purified diet (AIN-76). A modified AIN-76 mineral mixture was used, although the original calcium (Ca)/phosphorus (P) molar ratio remained unchanged. Rats were fed the modified diets for a period of 40 d before their kidneys were removed on the last day. Ca balance tests were performed on days 31 to 36 and biochemical analysis of urine was also studied. Kidney Ca, P, and magnesium (Mg) in the standard diet group (20% protein and 5% oil) were not affected by the mineral source. Kidney Ca, P, and Mg in the low-protein (10% protein) diet group, were found to be influenced by the dietary oil content and mineral source. In particular, the different mineral sources differentially increased kidney mineral accumulation. Pathological examination of the kidney showed that the degree of kidney calcification was proportional to the dietary oil content in the 10% dietary protein group, reflecting the calcium content of the kidney. The information gathered on mineral sources in this study will help future researchers studying the influence of dietary Ca/P molar ratios, and histological changes in the kidney.

Correspondence between Ca²âº and calciuria, citrate level and pH of urine in pediatric urolithiasis.

BACKGROUND: Hypercalciuria and hypocitraturia are considered the most important risk factors for urolithiasis. Citrate binds to urinary calcium to form a soluble complex which decreases the availability of ionized calcium (Ca(2+)) necessary for calcium oxalate formation and phosphate crystallization. The aims of this study were to assess the Ca(2+) fraction in relation to total calciuria, citraturia and urinary pH and to determine whether urinary Ca(2+) concentration is a helpful biomarker in metabolic evaluation of children with urolithiasis. METHODS: We collected 24-h urine samples from 123 stone-forming children and adolescents with hypocitraturia and from 424 healthy controls. Total calciuria (total calcium, Catotal), Ca(2+), pH, citrate, oxalate and Bonn Risk Index (BRI) were assessed and compared between the two groups. RESULTS: Total calciuria and Ca(2+) content were higher in stone-formers than in the healthy children. In both stone-formers and controls, Ca(2+) content was inversely related to citraturia and urinary pH, whereas the Ca(2+)/Catotal ratio differed slightly between the groups. A large variability in Ca(2+) level was found across individuals in both groups. The BRI increased with increasing calciuria and urine acidity. CONCLUSIONS: Compared to controls, stone-formers with hypocitraturia demonstrated a higher urinary Ca(2+) concentration, but this was proportional to calciuria. The large individual variability in urinary Ca(2+) content limits its practical use in metabolic evaluation of children with urolithiasis. However, the Ca/Citrate ratio may be a useful clinical tool in evaluating children with urolithiasis.

Dietary citrate treatment of polycystic kidney disease in rats.

Progression of autosomal-dominant polycystic kidney disease (ADPKD) in the heterozygous male Han:SPRD rat is dramatically slowed by ingestion of potassium or sodium citrate. This study examined the efficacy of delayed therapy with sodium citrate, the effect of sodium citrate therapy on kidney cortex levels of transforming growth factor-beta (TGF-beta), and the response to calcium citrate ingestion. Rats were provided with citrate salts in their food, and renal clearance, blood pressure, blood chemistry, and survival determinations were made. Sodium citrate therapy was most effective when started at age 1 month, and delay of therapy until age 3 months produced no benefit. Kidney cortex TGF-beta levels were elevated in 3- and 8-month-old rats with ADPKD, but not in 6-week-old rats. Sodium citrate treatment, started at age 1 month, lowered TGF-beta levels to normal in 3-month-old rats, but this is probably not the primary mechanism of citrate's beneficial effect. Calcium citrate had only a modest effect in preserving glomerular filtration rate. Effective treatment of ADPKD in this rat model requires early administration of a readily absorbed alkalinizing citrate salt. Existing data on ADPKD patients on vegetarian diets or with kidney stones should be studied in light of these findings.

1H NMR investigations of the molecular nature of low-molecular-mass calcium ions in biofluids.

High-resolution 1H NMR spectroscopy was employed to explore the complexation of Ca2+ by low-molecular-mass biomolecules in human saliva. The results acquired revealed that the organic acid anion (OAA) citrate acts as a powerful oxygen-donor chelator for salivary Ca2+, and accurate determination of its resonances' frequencies and spin-system pattern could be successfully utilized to determine its degree of saturation with this metal ion. Computer modelling studies demonstrated that the OAA lactate is the only competing salivary Ca2+ complexant available. Moreover, the Ca2+-complexation status of salivary citrate is substantially modified by dentifrice-mediated elevations in its concentration. 1H NMR analysis was also applied to determinations of the Ca2+ saturation status of citrate in a variety of alternative biofluids and the biochemical significance of these results is discussed.

Effects of water hardness on urinary risk factors for kidney stones in patients with idiopathic nephrolithiasis.

Both amount and timing of dietary calcium intake influence the recurrence of renal calcium stones. We have evaluated whether the hardness of extra meal drinking water modifies the risk for calcium stones. The urinary levels of calcium, oxalate and citrate, i.e., the main urinary risk factors for calcium stones, were measured in 18 patients with idiopathic nephrolithiasis, maintained at fixed dietary intake of calcium (800 mg/day), after drinking for 1 week 2 liters per day, between meals, of tap water and at the end of 1 week of the same amount of bottled hard (Ca2+ 255 mg/l) or soft (Ca2+ 22 mg/l, Fiuggi water) water, in a double-blind randomized, crossover fashion. As compared with both tap and soft water, hard water was associated with a significant 50% increase of the urinary calcium concentration in the absence of changes of oxalate excretion; the calcium-citrate index revealed a significant threefold increase during ingestion of hard water as compared with respect to soft water (Fiuggi water), making the latter preferable even when compared with tap water. This study suggests that, in the preventive approach to calcium nephrolithiasis, the extra meal intake of soft water is preferable to hard water, since it is associated with a lower risk for recurrence of calcium stones.