From the Guidelines
Elevated indirect serum bilirubin (unconjugated hyperbilirubinemia) is most commonly caused by hemolysis, impaired bilirubin uptake and conjugation in the liver, or a bilirubin metabolism deficiency, such as Gilbert's syndrome, as indicated by the most recent study 1. To determine the cause of elevated indirect serum bilirubin, a comprehensive approach is necessary. This includes:
- A thorough medical history and physical examination to identify potential causes such as hemolysis, liver disease, or inherited conditions.
- Targeted laboratory tests, including:
- Complete blood count to check for hemolysis, looking for decreased hemoglobin, elevated reticulocyte count, and abnormal peripheral blood smear.
- Additional hemolysis markers, such as elevated lactate dehydrogenase (LDH) and decreased haptoglobin.
- Tests for inherited conditions like Gilbert's syndrome, which can be suspected with a fasting bilirubin test, as levels typically rise after fasting.
- Hemoglobin electrophoresis for suspected hemoglobinopathies, such as sickle cell disease or thalassemia.
- Evaluation of liver function with tests including ALT, AST, alkaline phosphatase, and GGT to rule out mixed hepatic causes.
- Consideration of physiologic jaundice or conditions like Crigler-Najjar syndrome in newborns.
- If initial tests are inconclusive, more specialized testing may be needed, such as genetic testing for inherited disorders affecting bilirubin metabolism, as suggested by 1 and 1. The pattern of bilirubin elevation is crucial, with indirect hyperbilirubinemia typically indicating either increased bilirubin production from hemolysis or impaired bilirubin uptake and conjugation in the liver, as noted in 1.