Bilirubin

Bilirubin is the yellow waste your body makes when it recycles old red blood cells. It travels in two forms. First it rides on a protein (albumin) as 'unconjugated', or indirect, bilirubin. Then your liver takes it up, processes it (conjugation with glucuronic acid), and sends it out in bile. When total bilirubin runs high, doctors sort the cause into three buckets. Pre-hepatic means too much red-cell breakdown. Hepatic means the liver itself is struggling. Post-hepatic means a blocked bile duct. They tell them apart by which form dominates and which enzymes rise with it. A mild rise in the unconjugated form alone, as in the common, harmless Gilbert syndrome, is generally fine. It is even tied to a better heart-risk profile, maybe because bilirubin is an antioxidant. Severely high bilirubin is different: it signals advanced liver failure and feeds prognosis scores like MELD.

Last reviewed: June 22, 2026

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