Protein binding of bilirubin in plasma of anephric patients.

The protein binding of bilirubin was determined in the plasma of seven adult surgically anephric patients, eight adult physiologically anephric patients (creatinine clearance < 5 ml/min) and 13 adult normal volunteers. The determinations were carried out with undiluted plasma to which bilirubin, about 10 mg/100 ml, had been added. The free fraction of bilirubin in plasma (ratio of free to total concentration was (19.8 +/- 8.1) X 10(-5) in the surgically anephric, (10.4 +/- 4.0) X 10(-5) in the physiologically anephric, and (1.81 +/- 0.34) X 10(-5) in the normal subjects (mean +/- standard deviation). Based on this difference in plasma protein binding, patients in renal failure may be expected to have lower steady state plasma concentrations of total (free plus bound) bilirubin than do patients with normal renal function if the formation rate and intrinsic metabolic clearance of the pigment are the same as in normal subjects. This conclusion is consistent with available clinical evidence.