Prevalence of urinary metabolic disorders and risk factors of kidney stones in Iranian children

Introduction: Nephrolithiasis and urolithiasis, characterized by the formation of calculi in the kidney and lower urinary tract, respectively, pose a significant health concern for millions of children worldwide, particularly in developing countries. Objectives: This research aims to explore the prevalence of abnormal concentrations of urinary solutes as potential risk factors for kidney stones in Iranian children under the age of 14 years. Patients and Methods: A cross-sectional investigation spanning from January 2021 to January 2022 targeted children diagnosed with nephrolithiasis or urolithiasis through renal sonography, who were subsequently referred to the nephrology outpatient department of our hospital or our private pediatric nephrology office. Laboratory assessments encompassed urine calcium, oxalate, citrate, uric acid, creatinine, and urine cystine. Demographic attributes, stone composition (when available), and urinary metabolic disorders were scrutinized. Data analysis involved SPSS version 24, utilizing descriptive statistics such as mean, standard deviation, and frequency, categorized by variable type. Chi-square tests were employed for statistical analysis, with a significance threshold set at P<0.05. Results: The study encompassed 486 children, with a mean age of 55.58 months and a male majority of 50.8%. Among those with kidney stones, 77.2% exhibited unilateral stones, while 22.8% presented with bilateral stones. Predominant urinary metabolic disorders included hypercalciuria (30.2%), hyperuricosuria (22.6%), and hyperoxaluria (20.6%). Notably, 25.7% of the children manifested a combination of multiple metabolic disorders. Significant variations in the prevalence of hyperuricosuria were observed across different age groups. Boys exhibited higher incidences of hypercalcemia and metabolic abnormalities compared to girls, though no statistically significant differences were noted in other disorders. Conclusion: In summary, our findings indicate the presence of abnormal urinary metabolic risk factors in over half of children diagnosed with kidney stones. Hypercalciuria was the more frequent risk factor following hyperuricosuria and hyperoxaluria, cystinuria with prevalence of 30.2%, 22.6%, 20.6%, and (2.1%) respectively.