The Most Important Metabolic Risk Factors in Recurrent Urinary Stone Formers

Abstract

PURPOSE: To evaluate different urinary factors contributing to idiopathiccalcium stone disease for determining appropriate medical treatments.MATERIALS AND METHODS: Two 24-hour urine samples were collectedfrom 106 male recurrent idiopathic calcium stone formers and another 109randomly selected men as the control group matching for age.RESULTS: Cases had significantly higher mean urine oxalate, calcium, uricacid, and chloride in comparison with the healthy controls (P < .001).After necessary adjustment, only mean urine levels of oxalate and uricacid were higher in stone formers than those in controls. The mean valueof supersaturation for calcium oxalate was significantly higher in patientsthan the controls (P = .001); whereas supersaturation for calcium phosphateand uric acid did not reach statistical significe(P = .675 and P = .675,respectively). Hyperoxaluria and hypercalciuria were among the mostfrequent abnormalities. After categorizing urine parameter values into fourquartiles, the risk of stone formation was found to increase as the urinecalcium, oxalate, uric acid, chloride, and citrate rise. In contrast, the risk ofstone formation decreased with the increase of urine potassium.CONCLUSION: Oxalate seems to play the most important role as urinary stonerisk factor in our population followed by calcium and uric acid. In additionto the risk factors, it seems that supersaturation as the sum of all risk factorsprobably has a high predictive value.

Keywords

• kidney calculi
• risk factors
• calcium oxalate
• hypercalciuria
• hyperoxaluria