Introduction & Objective: Urinary stones are among the most common complaints referred to nephrologist and urologists. Although incidence of urolithiasis is low in children compared to adults and only 7% of all urinary stones are diagnosed before the age of 16 but stones are detected more frequently in pediatric age group in recent years. Metabolic derangements, infection, neurogenic bladder and urinary obstruction are major risk factors of urolithiasis. Common metabolic risk factors of urolithiasis in children are hypercalciuria, uricosuria, hypocitraturia, hyperoxaluria, metabolic acidosis and cystinuria. There are many clinical studies about the frequency of these metabolic risk factors with different results reflecting difference in diet, geographic area and genetics in study populations. In this study we tried to evaluate the frequency of metabolic causes of urinary stones in children referred to Hamadan pediatric nephrology clinic.

Materials & Methods: In this cross sectional-descriptive study 156 patients referred due to urinary stones to pediatric nephrology clinic underwent thorough metabolic evaluations including: serum calcium,phosphorus, uric acid, creatinine and non fasting random urine sample for calcium, creatinine , uric acid , oxalate, citrate and cystine . urine solute: creatinine ratios were calculated and compared with normative data. Results: Of 156 patients 136(87.2%) had metabolic derangements including: hyperuricosuria in 71 (45.5%), hypercalciuria in 41(26.3%), hypocitraturia in 26 (16.7%), hyperoxaluria in 16(10.3%),cystinuria in 1(0.6%) and metabolic acidosis in 39 (25%).

Conclusion: High rate of metabolic derangement in pediatric urinary stone patients mandates proper metabolic evaluation in all of them. hyperuricosuria was the most common metbolic finding instead of hypercalciuria in this study. This could be due to differences in diet, geographic area and genetic background in various populations.