Educational review: role of the pediatric nephrologists in the work-up and management of kidney stones.

BACKGROUND: The incidence of nephrolithiasis in children and adolescents is increasing and appears to double every 10 years. The most important role of the pediatric nephrologist is to diagnose and modify various metabolic and non-metabolic risk factors, as well as prevent long-term complications especially in the case of recurrent nephrolithiasis. OBJECTIVE: The purpose of this review is to summarize the existing literature on the etiology and management of pediatric nephrolithiasis. RESULTS: The incidence of kidney stones is increasing; dietary and environmental factors are probably the main causes for this increased incidence. In most pediatric patients, the etiology for the kidney stones can be identified. Metabolic factors, such as hypercalciuria and hypocitraturia, urinary tract infection, and urinary stasis, constitute leading causes. Herein, we review the etiologies, diagnostic work-up, and treatment options for the most prevalent causes of kidney stones. The detrimental effects of excessive dietary sodium, reduced fluid intake, and the benefits of plant-based over animal-based protein consumption on urinary crystal formation are discussed. We also review the long-term complications. CONCLUSIONS: Pediatric nephrologists have an important role in the diagnostic work-up and prevention of recurring nephrolithiasis.

Effect of urine pH and magnesium on calcium oxalate saturation.

Hypomagnesiuria is a common biochemical finding in patients with calcium oxalate (CaOx) nephrolithiasis. Clinical trials using Mg supplements as therapy against CaOx stones have shown mixed results. We tested the effect of Mg administration in healthy subjects under conditions of controlled urine pH (UpH) on urinary Ca excretion rate (UCaV) and CaOx saturation. This is a 4-phase, double blind, placebo-controlled, metabolic crossover study performed in healthy volunteers. Mg lactate (MgLact2) was used as Mg supplement. High UpH and low UpH were achieved by administration of potassium citrate (K3Citrate) and ammonium chloride (NH4Cl), respectively, with potassium balance maintained by KCl. Eight participants completed 4 phases of study. The interventions successfully modulated 24-h UpH (7.0 ± 0.4 vs. 5.7 ± 0.6 in high vs low pH phases; P<0.001). Administration of MgLact2 increased UMgV [175.8 ± 40.2 vs 93.4 ± 39.7 mg/day (7.2 ± 1.7 vs 3.8 ± 1.6 mmol/day), high vs low Mg phase; P<0.001], and increased pH both at low (5.6 ± 0.5 to 5.8 ± 0.7; P = 0.02) and high UpH (6.9 ± 0.4 to 7.0 ± 0.3; P = 0.01). At a given urine pH, Mg supplementation marginally increased UCaV, but did not alter UOxV or CaOx saturation. Provision of an alkali load significantly lowered UCaV and saturation of CaOx at any level of UMgV. Compared to changes in UMgV, changes in UpH play a more significant role in determining urine CaOx saturation in healthy subjects. Mg supplements are likely to reduce CaOx saturation if they also raise urine pH.

Evaluation of urinary abnormalities in nephrolithiasis patients from Marathwada region.

Urinary abnormalities were evaluated in 100 renal stone patients with first episode of renal stone having age 22 to 45 years from both sex and compared to 100 normal healthy control group having same age group from both sex. Twenty-four hours urinary oxalate, calcium, uric acid, sodium, magnesium, phosphorus and citrate were estimated. The urinary pH was also determined. In stone formers urinary oxalate, calcium, sodium and uric acid excretions were significantly higher when compared with control group. Whereas citrate, phosphate and magnesium excretion were significantly lower in stone formers when compared with control.The pH of urine in stone formers was lower than the controls. High dietary intake of purine rich diet causes elevated excretion of uric acid, which leads to calcium oxalate crystal formation and precipitation. Other risk factors such as urinary oxalate, calcium also related to formation of renal calculi.Hypocitraturia is the main cause of renal calculi along with hypomagnesiuria and hypophosphaturia in the patient of Marathwada region. On the basis of urinary abnormalities further stone formation in the patient can be prevented by dietary modifications.