Bilirubin is derived from haem and transported to the liver
bound mainly to albumin (unconjugated bilirubin). In the liver
bilirubin is conjugated with glucuronic acid (conjugated bilirubin)
which makes it water soluble and is excreted in bile.
Serum bilirubin levels are a balance between production and
clearance. The liver has a large capacity for conjugation of
bilirubin. Bilirubin is therefore a relatively insensitive test of
liver disease. Increased levels of conjugated bilirubin are seen in
cholestasis. Gilberts syndrome is a common cause of isolated
hyperbilirubinaemia due to increased unconjugated bilirubin.
Most common chronic haemolytic disorders present with mild
unconjugated hyperbilirubinaemia. In adults, quantitation of
conjugated bilirubin is seldom necessary unless intra-vascular
haemolysis is suspected. However, measurement of conjugated
bilirubin is important in assessment of neonatal jaundice.
Part of Profile
Liver Function Test
Request on ICE
Serum in gold-top vacutainer
Causes for Rejection
Unlabelled or incorrectly labelled sample;
Total Bilirubin: <21 umol/L