Liver and intrahepatic bile ducts - nontumor
Unconjugated hyperbilirubinemia

Topic Completed: 1 May 2012

Revised: 23 January 2019, last major update May 2012

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Unconjugated hyperbilirubinemia[TI] liver

Komal Arora, M.D.
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Table of Contents
Definition / general
Cite this page: Arora K. Unconjugated hyperbilirubinemia. website. Accessed March 31st, 2020.
Definition / general
  • Due to excessive production, reduced hepatic intake or impaired conjugation
  • Excessive production: hemolytic anemia, internal hemorrhage with blood resorption, ineffective hematopoiesis
  • Reduced hepatic uptake: Gilbert syndrome (some cases), drug interference with membrane carrier system
  • Impaired conjugation: physiologic jaundice of newborn (decreased UGT activity and decreased excretion because hepatic function does not fully mature until 2 weeks old), breast milk jaundice, genetic deficiency of UGT (Crigler-Najjar syndrome types I and II), Gilbert syndrome (some cases), diffuse hepatocellular disease (hepatitis, cirrhosis)
  • Crigler-Najjar syndrome type I: autosomal recessive, no UGT activity, fatal in neonates due to kernicterus
  • Crigler-Najjar syndrome type II: autosomal dominant, decreased UGT activity, mild kernicterus; yellow skin
  • Gilbert syndrome: may be autosomal dominant, UGT activity is 30% of normal due to mutations in promoter region, asymptomatic, affects 6% of US population, detected during periods of stress (illness, strenuous exercise, fasting, Eur J Pediatr 2012;171:11); living donor liver transplantation safe for both Gilbert disease donors and their recipients (Exp Clin Transplant 2012;10:39)
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