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Definition / generalCite this page: Arora K. Unconjugated hyperbilirubinemia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/liverunconjugatedhyper.html. Accessed April 23rd, 2019.
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)
