Renal Stones of Calcium Phosphate: Physicochemical Basis for Their Formation

Abstract

Summary The activity product of Ca²⁺ and HPO₄²⁻ was calculated for the urine before and after incubation with brushite (CaHPO₄ · 2H₂O). This permitted an estimation of the degree of saturation of urine in terms of Ca²⁺ and HPO₄²⁻. The urine of patients with idiopathic hypercalciuria was supersaturated with respect to brushite at all pH. However, the urine of normocalciuric subjects with stone was supersaturated only at high urinary pH.