conjugated hyperbilirubinaemia
Last reviewed 01/2018
Conjugated or direct hyperbilirubinaemia occurs when the the liver is able to conjugate bilirubin, but the excretion is impaired.
Causes include:
- failure of bilirubin excretion by hepatocytes:
- Dubin-Johnson syndrome
- Rotor's syndrome
- obstruction to biliary flow i.e. cholestasis, both intra-hepatic and extra-hepatic
The proportion of conjugated bilirubin with respect to the total raised bilirubin can give a clue as to cause of jaundice.
20-40% of total: more suggestive of hepatic than posthepatic jaundice
40-60% of total: occurs in either hepatic or posthepatic causes
> 50% of total: more suggestive of posthepatic than hepatic jaundice
Note that if conjugated bilirubin is less than 20% of total then the cause of hyperbilirubinaemia is secondary to haemolysis or constitutional e.g. Gilbert's disease, Crigler-Najjar syndrome