BILIRUBIN

1. A bile pigment whose measurement can be used as an indication of the health of the liver. 2. A substance released from old or damaged red blood cells. Small amounts of bilirubin normally enter the bloodstream and circulate until they reach the liver and then into the bowel, where bilirubin is further broken down and excreted. The normal value is 0.1 to 1.5 milligrams per liter of blood.