胆红素 (bilirubin) is a yellow compound that occurs in the body when red blood cells break down. It is produced in the liver and is a key component of bile, which helps in digestion. High levels of 胆红素 can lead to jaundice, a condition where the skin and eyes turn yellow. 胆红素 is typically processed by the liver and excreted in stool. There are two main types: unconjugated (indirect) and conjugated (direct) 胆红素. Conditions affecting the liver, such as hepatitis or cirrhosis, can disrupt this process, leading to elevated levels in the bloodstream.