A yellow-orange substance produced mainly from the breakdown of hemoglobin and processed by the liver for elimination from the body.
When red blood cells reach the end of their normal lifespan, hemoglobin is broken down and bilirubin is produced. The liver modifies bilirubin and excretes it into bile, which eventually leaves the body through the digestive tract.
Abnormally high bilirubin levels can occur because of increased red blood cell breakdown, impaired liver processing, or obstruction of bile flow and can result in jaundice.
QUICK FACT
Bilirubin is one reason that jaundice causes yellow discoloration of the skin and whites of the eyes.
COMMONLY CONFUSED WITH
Hemoglobin: the oxygen-carrying protein in red blood cells; bilirubin is produced partly from its breakdown.
SEE ALSO