Fasting Urinary Calcium and Adenosine 3′,5′-Monophosphate: A Discriminant Analysis for the Identification of Renal and Absorptive Hypercalciurias*

Abstract

Abstract Fasting urinary calcium and cAMP were determined in 45 control subjects, 51 patients with absorptive hypercalciuria, and 20 patients with renal hypercalciuria. The mean fasting urinary Ca was significantly higher in absorptive hypercalciuria than in the control group [0.077 ± 0.026 vs. 0.053 ± 0.027 (SD) mg/100 ml glomerular filtration (GF); P < 0.001]. Although the mean fasting urinary Ca of 0.174 ± 0.060 mg/100 ml GF and the value for cAMP in renal hypercalciuria were both significantly higher than those in other groups, the individual values for fasting urinary cAMP overlapped widely into the ranges found in the control and absorptive hypercalciuria groups. In the control group, fasting urinary calcium was inversely correlated with fasting urinary cAMP (P < 0.05). Values in absorptive hypercalciuria were within 2 SES of estimate for the control group, though they were higher in calcium and lower in cAMP. When the contribution of absorbed calcium was reduced by prior administration of sodium ce...