Bilirubin is a yellow-orange pigment produced when old red blood cells are broken down. The liver processes it and removes it in bile. When it builds up, the skin and eyes can turn yellow — a sign called jaundice.
Direct vs indirect bilirubin
Total bilirubin is split into two parts. Direct (conjugated) bilirubin has been processed by the liver; a high level points toward a liver or bile-duct problem. Indirect (unconjugated) bilirubin rises when red cells are broken down faster than the liver can keep up, or in harmless conditions such as Gilbert's syndrome.
Common causes of high bilirubin
- Gilbert's syndrome — a common, harmless inherited variation
- Liver inflammation (hepatitis) or fatty liver
- Blocked bile ducts, for example from gallstones
- Increased red cell breakdown (hemolysis)
Reading it with the rest of the panel
Bilirubin is interpreted alongside liver enzymes such as ALT, AST and ALP. The pattern between them helps your doctor tell a liver problem from a bile-duct blockage.
You don't have to interpret a single number alone. Upload your full lab report and Lab Lens will explain every value in plain English, or browse all our lab test guides.
This article is for general education only and is not medical advice. Reference ranges vary between laboratories — always read your result against the range on your own report and discuss it with your doctor.