Evaluating elevated bilirubin

Q: In conjugated (direct) hyperbilirubinemia, both unconjugated (indirect) and conjugated bilirubin are elevated. 

A) True

B) False

Answer: A

It is rarely appreciated that in conjugated hyperbilirubinemia, there is always some level of unconjugated hyperbilirubinemia.

The causes of conjugated hyperbilirubinemia are:

• hepatocellular disease
• impaired canalicular excretion of bilirubin, and/or 
• biliary obstruction

The causes of unconjugated hyperbilirubinemia are:

• overproduction of bilirubin
• impaired bilirubin uptake by the liver, and/or 
• abnormalities of bilirubin conjugation

#hepatology

#laboratory-medicine

References:

1. Shroff H, Maddur H. Isolated Elevated Bilirubin. Clin Liver Dis (Hoboken). 2020 May 7;15(4):153-156. doi: 10.1002/cld.944. PMID: 32395242; PMCID: PMC7206321.

2. Guerra Ruiz AR, Crespo J, López Martínez RM, Iruzubieta P, Casals Mercadal G, Lalana Garcés M, Lavin B, Morales Ruiz M. Measurement and clinical usefulness of bilirubin in liver disease. Adv Lab Med. 2021 Jul 9;2(3):352-372. doi: 10.1515/almed-2021-0047. PMID: 37362415; PMCID: PMC10197288.

3. VanWagner LB, Green RM. Evaluating elevated bilirubin levels in asymptomatic adults. JAMA. 2015 Feb 3;313(5):516-7. doi: 10.1001/jama.2014.12835. PMID: 25647209; PMCID: PMC4424929.