Pediatric Urinary Stone Composition in the United States

PurposeThe incidence of urolithiasis in children is increasing. However, stone composition studies in this population are limited. We sought to determine the effects of age, gender and geographical location on urinary stone composition in the United States pediatric population.Materials and MethodsWe obtained composition analyses for all urinary stones submitted to a reference laboratory between 2000 and 2009. Stones were excluded if the patient was younger than 1 year or older than 18 years. Stone composition was determined by Fourier transform infrared spectroscopy. Logistic regression analysis was performed to determine associations between stone composition frequency and age, gender and geographical region.ResultsA total of 5,245 stones were included in our analysis. Calcium was found in 89.2% of stones. The percentage of stones containing calcium oxalate increased, while magnesium ammonium phosphate and ammonium acid urate containing stones decreased with age. Calcium oxalate and magnesium ammonium phosphate containing stones were more common in females, while uric acid stones were more common in males. Additionally, significant differences in stone composition frequency were noted between males and females in specific age groups and between age groups within the same gender. Geographical distribution was not significantly associated with stone composition.ConclusionsThis series is the largest analysis to date of urinary stone composition in the pediatric population in the United States. Age and gender were significantly associated with stone composition, while geographical region was not significantly associated with stone composition.