Bilirubin is one of the important components of bile. It is the degradation product of hemoglobin in various heme proteins under the action of a series of enzymes. It is important to the digestion and absorption of lipids and the formation of yellow distemper. Bilirubin comes in two forms: water-soluble and water-insoluble. Bilirubin has powerful antioxidant, anti-inflammatory and autoimmune properties. The concentration of bilirubin in human body is related to sex, drug intake, age and so on. Low serum bilirubin is directly related to diabetes, metabolic syndrome, cardiovascular disease and other pathological states. However, high bilirubin is indicative of hemolysis, jaundice, Gilbert syndrome, hepatitis, drug toxicity, and possible bile duct obstruction.
