Bilirubin is a yellow pigment that’s in everyone’s blood and stool. Bilirubin is made in the body when the hemoglobin protein in old red blood cells is broken down. https://www.healthline.com/health/bilirubin-blood
A bilirubin test is used to help determine the cause of jaundice, a yellowing of your skin and the whites of your eyes. It helps diagnose conditions like liver disease, hemolytic anemia, and blocked bile ducts.
A small amount of your blood is needed to perform this test. The blood sample is obtained through venipuncture, where a needle is inserted into a vein through the skin in your arm or hand, and a small amount of blood is collected in a test tube.
If bilirubin is not being attached to the glucose-derived acid (conjugated) in the liver or is not being adequately removed from the blood, it can mean that there is damage to your liver. Testing for bilirubin in the blood is, therefore, a good way of testing for liver damage. In an older child or adult, normal values of direct bilirubin are from 0–0.4 milligrams per deciliter (mg/dL). Normal values of total bilirubin are from 0.3–1.0 mg/dL.