What is the pathophysiology of Gilbert syndrome?

Updated: May 21, 2019
  • Author: Hisham Nazer, MBBCh, FRCP, DTM&H; Chief Editor: BS Anand, MD  more...
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Hepatic bilirubin UGT activity is consistently decreased to approximately 30% of normal in individuals with Gilbert syndrome. Decreased bilirubin-UGT activity has been attributed to an expansion of thymine-adenine (TA) repeats in the promoter region of the UGT-1TA gene. Racial variation in the number of TA repeats and a correlation with enzyme activity suggest that these polymorphisms contribute to variations in bilirubin metabolism. An increased proportion of the bilirubin monoconjugates in bile reflects reduced transferase activity. [14, 25, 26, 27]

Fasting, febrile illness, alcohol, or exercise can exacerbate jaundice in patients with Gilbert syndrome. Hemolysis and mild icterus usually occur at times of stress, starvation, and infection.

Investigators have discovered that Gilbert syndrome may coexist with other liver diseases, such as nonalcoholic steatohepatitis. Therefore, unconjugated hyperbilirubinemia in patients with these other conditions may be due to Gilbert syndrome and should not always be attributed to the underlying liver disorder.

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