Bilirubin test

A bilirubin test measures the amount of bilirubin in your blood. Bilirubin is a substance produced when the liver breaks down old red blood cells. When bilirubin levels are high, the skin and whites of the eyes may look yellow (jaundice). This may be caused by liver disease.

The bilirubin test is used to:

• Check liver function and watch for signs of liver disease, such as hepatitis or cirrhosis, or the effects of medicines that can damage the liver.
• Find out if something is blocking the bile ducts. This may occur if gallstones, tumors of the pancreas, or other conditions are present.
• Diagnose conditions that cause increased destruction of red blood cells, such as hemolytic anemia or hemolytic disease of the newborn.
• Help make decisions about whether newborn babies with neonatal jaundice need treatment. These babies may need treatment with special lights, called phototherapy. In rare cases, blood transfusions may be needed.

• A health professional uses a needle to take a blood sample, usually from the arm.
• In babies, a heel stick is used to get a blood sample. The baby's heel is poked, and several drops of blood are collected. Your baby may have a tiny bruise where the heel was poked.

In general, there's nothing you have to do before this test, unless your doctor tells you to.

Normal values in adults

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

• Results that show slightly high bilirubin levels may be nothing to worry about. It could be caused by certain inherited diseases, such as Gilbert's syndrome. This is a condition that affects how the liver processes bilirubin. Some people with this problem get jaundice, but it's not harmful.
• High levels of bilirubin in the blood may be caused by:
  • Diseases that cause liver damage, such as hepatitis, cirrhosis, or mononucleosis.
  • Diseases that cause blockage of the bile ducts, such as gallstones or cancer of the pancreas.
  • Rapid destruction of red blood cells in the blood, such as from sickle cell disease or an allergic reaction to blood received during a transfusion (called a transfusion reaction).
  • Medicines that may increase bilirubin levels. This includes many antibiotics, some types of birth control pills, diazepam (Valium), and indomethacin (Indocin).

Low values

Low levels of bilirubin in the blood may be caused by:

• Medicines that may decrease bilirubin levels. An example is phenobarbital.

Normal values in newborns

Normal values in newborns depend on the age of the baby in hours and whether the baby was premature or full term. Normal values may vary from lab to lab.