[Use of the calcium-creatinine ratio in diagnosis and therapy]

Hypercalciuria is a major cause of urolithiasis in adults and has reached increasing attendance in childhood. Traditionally urinary excretion of calcium is evaluated by 24-hour urine collection. Previous reports proposed the urinary calcium/urinary creatinine ratio (Ca/Cr-ratio) to diagnose hypercalciuric states. In 10 children with normocalciuria and 8 children with hypercalciuria the values of calcium excretion and Ca/Cr-ratio in a 24-hour urine collection were compared. 40 analyses showed a significant correlation (p = 0.001, r = 0.91) and hypercalciuria (urinary calcium greater than 4 mg/kg/day) is present if the Ca/Cr-ratio exceeds 0.23 (mg/mg). In 10 of the 18 patients the Ca/Cr-ratio of the 24-hour collection was compared with the Ca/Cr-ratio of a random urine sample collected 3 hours after breakfast. No significant difference was present. In 9 of 10 patients the correct diagnosis (normocalciuria or hypercalciuria) was possible by evaluation of this random urine sample. Our studies indicate that the evaluation of Ca/Cr-ratio in a random urine sample is a simple and reliable method to detect hypercalciuria and should be performed in all children with urolithiasis or unexplained hematuria. It is also a simple test for early detection of hypercalciuria in patients with long-term administration of vitamin D metabolites.