What is bilirubin?

Bilirubin is made during the normal process of breaking down red blood cells. It is a yellowish substance found in bile, a fluid in your liver. This fluid helps digest food. A healthy liver moves most of the bilirubin from your body. If the liver is damaged, bilirubin can leak out into your blood.

If there is too much bilirubin in your blood, it can cause health problems. Bilirubin can also come out in the urine, causing it to look very dark.

Why is a bilirubin test done?

A bilirubin test is done to measure the levels of bilirubin in your blood.

If too much bilirubin is in your bloodstream it can cause jaundice, which can make your skin and eyes turn yellow. The results of the bilirubin test and signs of jaundice can help your doctor check your liver and determine if you have liver disease.

A bilirubin test is also used to determine jaundice in newborns. Many newborns do not have mature enough livers to get rid of bilirubin. High bilirubin levels in newborns can cause brain damage.

The test is usually done in conjunction with other tests for liver disease as part of a hepatic function panel. It can also be done to:

  • Diagnose hepatitis, cirrhosis, or other liver diseases
  • Find blockages in structures carrying bile from your liver
  • Monitor an existing liver disorder
  • Diagnose disorders related to red blood cell production problems
  • Test a patient who has history of drinking large amounts of alcohol
  • Test a patient who has a suspected drug toxicity

Last reviewed by a Cleveland Clinic medical professional on 06/14/2018.


U.S. National Library of Medicine. Bilirubin Blood Test. Accessed 6/21/2018.

American Liver Foundation. Liver Function Tests. Accessed 6/21/2018.

Lab Tests Online. Bilirubin. Accessed 6/21/2018.

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