EFFECT OF PHOTOTHERAPY AND EXCHANGE TRANSFUSION ON PRIMARY BILE ACIDS IN THE SERUM OF HYPERBILIRUBINAEMIC NEWBORNS

. Serum primary bile acid (cholic (CA) and chenodeoxycholic (CDCA) acid) concentrations were measured in 14 preterm and 11 full-term hyperbilirubinaemic newborns at the beginning and end of, and 24 and 72 hours following phototherapy. Only in the preterm newborns with gestational ages of 35-38 weeks there was a significant decrease of mean serum bile acid concentrations which could be shown 72 hours after the beginning of phototherapy. It can be hypothesized that the decrease was a result of a direct effect of light on the excretory liver function. Serum CA and CDCA concentrations were also measured in 5 hyperbilirubinaemic newborns at the beginning and end, and 24, 48 and 72 hours after the end of exchange transfusion. Exchange transfusion caused a clear immediate decrease in the mean serum primary bile acid concentrations. However, on day 2 after exchange transfusion the mean serum concentration of CA was about 150% and that of CDCA about 110% of the initial values. The most hyperbilirubinaemic newborns had extremely high primary bile acid serum concentrations before therapy. As bile acids compete with bilirubin for albumin binding it should be considered whether high bile acids in the serum of hyperbilirubinaemic newborns presuppose exchange transfusions.