Abstract
Untrafiltrates were prepared at 37[degree]C in an atmosphere of 5% CO2 from plasma samples obtained from 4 dogs, 15 normal men and women and from 32 patients with varying degrees of azotemia. In the normal subjects, an average of 1/4 of the inorganic phosphate of plasma was found to be protein bound. This binding was not dependent upon the presence of Ca or Mg. In patients with azotemia, with or without phosphate retention, the fraction of plasma inorganic phosphate bound to protein was not significantly different.