Defects in bile pigment metabolism causing jaundice

The excretion of bilirubin and therefore the relief of jaundice is dependent upon at least three factors. First, the bilirubin must be conjugated and thus converted into a water soluble compound: this means its conversion to an ester glucuronide although other conjugates may also be formed. Secondly, there is the problem of the transport of bilirubin through the hepatic cell. A defect in either the up-take of bilirubin or the secretion of conjugated bilirubin may result in jaundice such as is seen in the various types of familial hyperbilirubinemia. Thirdly, there is the possibility of alternative catabolic pathways for bilirubin: this approach to the problem has, however, not yet received the attention of investigators.