Objectives: To determine which risk factors help predict recurrent stone formation. Urinary stone disease is relatively rare in children. At our institution, a full urinary metabolic evaluation is initiated after the first stone episode.
Methods: A retrospective cohort study was performed to assess urinary metabolic profiles in children with urolithiasis. Twenty-four-hour urine collections were performed and evaluated. Urine chemistries were adjusted for creatinine and weight. Abnormal thresholds were obtained from the available published data. The patients were stratified into solitary or recurrent stone formers by review of the medical record. Multivariate analysis was performed with a logistic regression model to assess for independent risk factors for stone recurrence.
Results: A total of 148 samples from 88 patients with solitary stones and 84 samples from 51 patients with recurrent stones were evaluated. Age and gender were well-matched between the 2 groups. Most known stones were calcium oxalate, and there were no radiolucent stones in those with unknown composition. A significantly higher number of patients with recurrent stones had abnormal values for calcium (73% vs 57%) and citrate (30% vs 13%) by univariate analysis. Both calcium (odds ratio, 2.3, P <.01) and citrate (odds ratio, 3.5, P <.001) remained independent risk factors for stone recurrence by multivariate analysis.
Conclusions: There are significant differences in the urinary calcium and citrate levels between children with solitary and recurrent calcium stone formation. This may allow identification of patients at risk for stone recurrence that may benefit from more aggressive dietary and/or pharmacologic intervention.
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