Laboratory Findings in Gilbert's Disease

Core Diagnostic Laboratory Criteria

The American Gastroenterological Association notes that total bilirubin is mildly elevated, typically 1.5-3 mg/dL, but rarely exceeds 4-5 mg/dL, in patients with Gilbert's disease 1
The European Association for the Study of the Liver states that unconjugated bilirubin comprises more than 70-80% of total bilirubin in Gilbert's disease 1, 2
The American Association for the Study of Liver Diseases recommends that conjugated bilirubin must be less than 20-30% of total bilirubin to confirm the diagnosis of Gilbert's disease 1, 2
The American College of Gastroenterology notes that ALT and AST remain normal in patients with Gilbert's disease 3
Alkaline phosphatase and GGT are normal in patients with Gilbert's disease, according to the American Gastroenterological Association 2, 3
The European Association for the Study of the Liver states that all other liver function tests, including albumin and prothrombin time, are normal in Gilbert's disease 3

The American Society of Hematology notes that complete blood count is normal, excluding hemolysis as a cause, in patients with Gilbert's disease 1, 3
The International Society of Hematology states that there is no evidence of hemolytic anemia on peripheral smear in Gilbert's disease 3

The American Gastroenterological Association warns that the terms "direct" and "conjugated" bilirubin are often incorrectly used interchangeably, and for accurate diagnosis of Gilbert's disease, specifically request conjugated bilirubin fraction, not just "direct" bilirubin 1
The European Association for the Study of the Liver notes that direct bilirubin includes both conjugated bilirubin and delta bilirubin, which has a 21-day half-life 1, 4

The American College of Gastroenterology states that Gilbert's syndrome affects 5-10% of the population, with males predominating approximately 5:1, and accurate identification is important to avoid misdiagnosis as drug-induced liver injury 1, 2