Diagnosis and Evaluation of Gilbert Syndrome

Initial Laboratory Evaluation

The American College of Gastroenterology recommends a complete liver function panel including total bilirubin, direct (conjugated) and indirect (unconjugated) bilirubin fractionation to diagnose Gilbert syndrome 1
Calculate the proportion of conjugated bilirubin, which should be less than 20-30% of total bilirubin in Gilbert syndrome, as suggested by the American Association for the Study of Liver Diseases 1
A complete blood count is necessary to rule out hemolysis, according to the American College of Gastroenterology 2
Serum electrolytes and kidney function tests should be performed, as recommended by the American College of Radiology 3

The American College of Gastroenterology suggests ruling out hemolytic disorders through reticulocyte count, haptoglobin, LDH, and peripheral blood smear 2
The American College of Radiology recommends ruling out other liver diseases that may cause hyperbilirubinemia 3

The American College of Radiology suggests that abdominal ultrasound may be performed to rule out structural liver or biliary tract abnormalities, though this is not mandatory if other tests are normal 3

The American Association for the Study of Liver Diseases recommends close monitoring in patients with persistent isolated elevations of direct bilirubin, as this may indicate drug-induced liver injury rather than Gilbert syndrome 1
The American College of Gastroenterology suggests that a breakdown of the direct bilirubin fraction into conjugated and delta bilirubin should be considered if the etiology of prolonged hyperbilirubinemia remains unclear 1