[Liver diseases in infants. Metabolism and transport of bilirubin and bile acids].

Bilirubin, a degradation product of heme, is taken up from the blood by the liver parenchymal cells (hepatocytes), metabolized and secreted into bile. Bile acids are synthesized from cholesterol in hepatocytes and secreted into bile. After secretion into the intestine, metabolites of bilirubin and bile acids are partially taken up in the portal circulation and transferred to the liver, where these substances are extracted from the blood and secreted again into bile (enterohepatic circulation). In this article, we discuss several aspects of hepatic uptake, metabolism and secretion of bilirubin and bile acids.