Renal Reabsorption of Phosphate in Normal Human Subjects and in Patients with Parathyroid Disease

A number of studies in the dog and in man (1-6) have demonstrated a maximal renal tubu- lar reabsorptive capacity for phosphate (TmP 8). However, some investigators have denied that the reabsorption of phosphate conforms to Tm charac- teristics (7-9). These workers have suggested that phosphate reabsorption is conditioned by the rate of phosphate filtration such that a fairly constant proportion of the filtered phosphate is reab- sorbed. In view of the conflicting evidence and the relative paucity of phosphate titration studies on man, experiments were performed in order to obtain information on the mechanism of phosphate reabsorption, the constancy of reabsorption in any one individual, and its variability in a group of subjects. The data were required for subsequent investigations designed to evaluate the influence of several factors on renal phosphate transport. The studies were performed on normal individuals and in patients with parathyroid disease.