Bilirubin (English: Bilirubin) is a kind of bile pigment, which is the main pigment of human bile and is orange-yellow. It is the main metabolite of heme in the body, it is toxic and can cause irreversible damage to the brain and nervous system, but it also has antioxidant function, which can inhibit the oxidation of linoleic acid and phospholipids. Bilirubin is an important basis for clinical judgment of jaundice and an important indicator of liver function.