What is bilirubin, and what does high bilirubin mean?
Last content review 2026-09-23
The short answer
Bilirubin is a yellow pigment made when old red blood cells are broken down. The liver processes it and removes it in bile. A high bilirubin level can come from increased red-cell breakdown, reduced processing in the liver, or blocked bile flow — and in many people a mild rise reflects a harmless inherited variation called Gilbert syndrome.
What is happening?
Reports often show total, direct (conjugated) and indirect (unconjugated) bilirubin. Which fraction is raised helps point to the likely cause.
Very high bilirubin can make the skin or eyes look yellow (jaundice), which always deserves prompt medical assessment.
Why does this matter?
Bilirubin should be interpreted with the other LFT values, the blood count and symptoms; a single mildly raised value is often not a sign of liver damage.
What does the evidence say?
MedlinePlus explains that high bilirubin can result from liver disease, bile-duct blockage or increased red-cell breakdown, and that Gilbert syndrome is a common, generally harmless cause of mildly high levels.
The ACG guideline (2017) recommends fractionating raised bilirubin to distinguish conjugated from unconjugated causes.
Key takeaway
High bilirubin has several possible causes; jaundice needs prompt review, while an isolated mild rise is frequently benign.
Sources & references
US National Library of Medicine (MedlinePlus)
Bilirubin Blood Test · Official health information
View original sourceAmerican College of Gastroenterology
ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries (2017) · Clinical guideline
View original source
This page is general health education. It is not a diagnosis, and it cannot replace advice from your treating doctor. Never start or stop a prescribed medicine based on what you read here.