Metabolic syndrome in obese adolescents is associated with risk for nephrolithiasis.

Objectives: To examine the relationship between urinary pH and metabolic syndrome risk factors along with insulin resistance in obese adolescents, and to evaluate the relationship between other urinary stone-forming and -inhibiting markers and metabolic syndrome.

Study Design: A total of 46 obese adolescents were enrolled. Twenty-four hour and randomly obtained urine samples were analyzed for urinary pH, promoters of stone formation (ie, uric acid, oxalate, and relative saturation ratio of calcium oxalate [RSR-CaOx]), and inhibitors of stone formation (ie, citrate and osteopontin). Other data collected included height, weight, blood pressure, and fasting lipid, insulin, and glucose levels.

Results: The subjects had a mean age of 14.6±2.0 years and a mean body mass index of 36±6.3 kg/m(2). Random urine pH and the number of risk factors for metabolic syndrome were negatively correlated (r=-0.34; P=.02). RSR-CaOx was correlated with both homeostasis model assessment of insulin resistance score (r=0.38; P<.01) and number of risk factors for metabolic syndrome (r=0.47; P=.001)

Conclusion: Decreased urinary pH and increased RSR-CaOx are associated with risk factors for metabolic syndrome in obese adolescents.