Do Overweight and Obese Pediatric Stone Formers Have Differences in Metabolic Abnormalities Compared With Normal-weight Stone Formers?

OBJECTIVE: To determine if 24-hour urinary parameters in children with nephrolithiasis across 4 institutions were influenced by body mass index (BMI).

MATERIALS AND METHODS: The 24-hour urinary parameters obtained from children with nephrolithiasis between 2000 and 2013 were stratified by BMI percentile ≥85th and <85th (overweight and obese patients vs healthy weight, respectively). A total of 206 children were included in the study. Exclusion criteria included patients with a history of spina bifida, neurogenic bladder, and cerebral palsy, and patients on medical treatment before the first 24-hour urine collection.

RESULTS: Overweight and obese patients consisted of 35.4% of the cohort (n = 73). Metabolic abnormalities were present in 130 children (63.1%). The most common abnormality present in the <85th percentile was hypercalciuria (32.3%), and in the ≥85th percentile, hyperoxaluria (37.0%). Univariable and multivariable analyses revealed that overweight and obese children were more likely to have low urinary volume and elevated uric acid compared to normal-weight children.

CONCLUSION: Although there is a link between stone formation and BMI in adults, no definitive conclusions have been proven in the pediatric literature. Our study indicates that stone-forming children who are overweight or obese have low urinary volume and elevated uric acid compared to normal-weight stone-forming children.