Diseases or conditions which, through hemolytic processes, produce bilirubin faster than the liver can metabolize it, cause the levels of unconjugated (indirect) bilirubin to increase in the circulation. Liver immaturity and several other diseases in which the bilirubin conjugation mechanism is impaired cause similar elevations of circulating unconjugated bilirubin. Bile duct obstruction or damage to hepatocellular structure causes increases in the levels of both conjugated (direct) and unconjugated (indirect) bilirubin in the circulation.

Please note: the methods used for total bilirubin and direct bilirubin do not directly correlate. As such, calculated indirect bilirubin and/or percentage conjugation are not reported, and such calculations are not appropriate or valid.

Ascorbic acid (up to 50mg/dL) does not interfere with measurement. Please contact laboratory for further information on interferences.