Metabolic evaluation of urolithiasis and obesity in a midwestern pediatric population.

Purpose: The incidence of urolithiasis has been proved to be increasing in the adult population, and evidence to date suggests that the same holds true for the pediatric population. While adult urolithiasis is clearly linked to obesity, studies of pediatric patients have been less conclusive. We hypothesized that a population of otherwise healthy children with stones would have an increased body mass index compared to a control population, and that obese pediatric stone formers would have results on metabolic assessment that are distinct from nonobese stone formers. Materials and Methods: We retrospectively reviewed the charts of all patients 10 to 17 years old with upper tract urolithiasis without comorbidities treated between 2006 and 2011. Mean body mass index of our population was compared to state data, and 24-hour urine collection results were compared between obese and nonobese patients with stones. Results: The obesity rate in 117 patients with urolithiasis did not differ significantly from the obesity rate derived from the 2007 National Survey of Children's Health (observed/expected ratio 1.11, 95% CI 0.54-1.95). Using t-test and chi-square comparisons, overall 24-hour urine collection data did not show statistically significant differences. Conclusions: Our results do not confirm obesity as a risk factor for pediatric urolithiasis in otherwise healthy patients. We also found no substantial metabolic differences between healthy nonobese stone formers and obese patients. While the pediatric literature is mixed, our study supports the majority of published series that have failed to establish a link between pediatric urolithiasis and obesity.