Hematin and Bilirubin Binding to Human Serum Albumin and Newborn Serum

Abstract

In jaundiced newborn infants, hemolytic disease is considered a risk factor for kernicterus due to the suspected competition between bilirubin and other Hb breakdown products for albumin binding. The effect of hematin on bilirubin-albumin binding was studied using the peroxidase assay and a light-scattering technique for measuring unbound bilirubin. Hematin does not affect bilirubin-albumin binding. To determine if other albumin binding functions are affected by hematin, a microdialysis rate technique was used employing 2 ligands, diazepam and monoacetyldiaminodiphenyl sulfone (MADDS). Hematin does not utilize the diazepam binding function of albumin, but does decrease the albumin binding of MADDS. The MADDS and bilirubin binding functions are not identical. The clinical usefulness of reserve albumin equivalent determination using MADDS is discussed.