Albumin reserve for binding of bilirubin in maternal and cord serum under treatment with sulphasalazine.

Twelve pregnant patients with ulcerative colitis or Crohn's disease who were being treated with sulphasalazine (SASP) were studied together with their newborn, full-term babies. An earlier study had shown almost identical concentrations of SASP and its metabolic sulphapyridine (SP) in maternal and cord serum. As controls, blood samples were collected from 25 healthy women and their newborn infants. Sera from mothers and infants were analysed for the vacant amount of high-affinity bilirubin binding site on albumin (reserve albumin) by the MADDS method. The mean reserve albumin concentration of the SASP-treated mothers was 9% lower than that of the controls, which is probably insignificant. No difference was observed in the corresponding two groups of infants. In vitro studies showed that neither SASP nor SP in therapeutic plasma concentrations had a significant bilirubin-displacing capacity. It seems that SASP preferentially is bound to other sites on albumin than to the high-affinity binding site for bilirubin. The risk of kernicterus in the full-term newborn does not seem to be increased by treatment of the mother with sulphasalazine.