Random urinary calcium/creatinine ratio for screening hypercalciuria in children with hematuria

Abstract

Background: Hypercalciuria is one of the most common causes of unexplained isolated hematuria. The diagnostic methods for hypercalciuria have not yet been standardized. The aim of this study was to assess whether random urinary calcium/creatinine ratio could be used as a screening tool for hypercalciuria in children with hematuria. Methods: This prospective study included 264 children with primary hematuria for whom both random and 24 hr urinary evaluations were performed. Pearson correlation and ROC curve were used to assess the correlations. A multiple linear regression model was used to analyze effects of age, weight, height, body mass index, and body surface area on random urinary calcium/creatinine ratio. Results: There was a moderately strong correlation between random urinary calcium/creatinine ratio and 24 hr urinary calcium excretion (r=0.584, P<0.001). The most appropriate cutoff value of random urinary calcium/creatinine ratio for the estimation of hypercalciuria was 0.075 mg/mg (sensitivity, 77.8%; specificity, 64.3%; area under the curve, 0.778). Body mass index and 24 hr urinary calcium excretion significantly affected random urinary calcium/creatinine ratio with a low coefficient of determination (r2=0.380, P<0.001). Conclusions: Random urinary calcium/creatinine ratio is not suitable for screening hypercalciuria in children with hematuria. Twenty-four hour urinary analysis should be performed to diagnose hypercalciuria in children with hematuria. © The Korean Society for Laboratory Medicine.