Dialyzability, Protein Binding, and Renal Excretion of Plasma Conjugated Bilirubin*

Abstract

Conjugated bilirubin is excreted in the urine, but unconjugated bilirubin is generally believed not to be excreted by the kidneys. The basis for this difference has not been resolved by past stud- ies. Hoover and Blankenhorn reported that bili- rubin was dialyzable only from the plasma of patients who had bilirubinuria, and that it was not dialyzable from the plasma of patients with acho- luric jaundice (3). Most subsequent investigators, however, have maintained that neither con- jugated nor unconjugated bilirubin was dialyz- able or ultrafilterable from plasma (4-7). This led to the hypothesis that conjugated bilirubin was probably excreted in the urine by a process of renal tubular secretion