What Is a Bilirubin Test?

Medically Reviewed by Sabrina Felson, MD on February 06, 2021

A bilirubin test measures the amount of bilirubin in your blood. It’s used to help find the cause of health conditions like jaundice, anemia, and liver disease.

Bilirubin is an orange-yellow pigment that occurs normally when part of your red blood cells break down. Your liver takes the bilirubin from your blood and changes its chemical make-up so that most of it is passed through your poop as bile.

If your bilirubin levels are higher than normal, it’s a sign that either your red blood cells are breaking down at an unusual rate or that your liver isn’t breaking down waste properly and clearing the bilirubin from your blood.

Another option is that there’s a problem somewhere along the pathway that gets the bilirubin out of your liver and into your stool.

Why Do You Get This Test?

In children and adults, doctors use it to diagnose and monitor liver and bile duct diseases. These include cirrhosis, hepatitis, and gallstones.

It’ll also help determine if you have sickle cell disease or other conditions that cause hemolytic anemia. That’s a disorder where red blood cells are destroyed faster than they’re made.

High levels of bilirubin can cause a yellowing of your skin and eyes, a condition doctors call jaundice.

High bilirubin levels are common in newborns. Doctors use the age of the newborn and the bilirubin type and levels to determine if treatment is necessary.

What Happens During the Test?

A nurse or lab technician will draw blood through a small needle inserted into a vein in your arm. The blood is collected in a tube.

With newborns, blood is usually drawn by using a needle to break the skin of the heel.

Your doctor will send the blood to a lab for analysis.

Before the test, tell your doctor about how active you’ve been and what food and medicines you’ve taken. Certain medications may alter your results.

After the test, you’ll be able to continue with your normal activities right away.

Who Should Get It? Who Shouldn’t?

Your doctor may order a bilirubin test if you:

  • Show signs of jaundice
  • Have anemia, or low red blood cells
  • Might be having a toxic reaction to drugs
  • Have a history of heavy drinking
  • Have been exposed to hepatitis viruses
  • Have cirrhosis

You might also have your bilirubin tested if you have symptoms like:

What Do the Results Mean?

A bilirubin test measures total bilirubin. It can also give levels of two different types of bilirubin: unconjugated and conjugated.

Unconjugated (“indirect”) bilirubin. This is the bilirubin created from red blood cell breakdown. It travels in the blood to the liver.

Conjugated (“direct”) bilirubin. This is the bilirubin once it reaches the liver and undergoes a chemical change. It moves to the intestines before being removed through your stool.

For adults over 18, normal total bilirubin can be up to 1.2 milligrams per deciliter (mg/dl) of blood. For those under 18, the normal level will be will be 1 mg/dl. Normal results for conjugated (direct) bilirubin should be less than 0.3 mg/dl.

Men tend to have slightly higher bilirubin levels than women. African-Americans tend to have lower bilirubin levels than people of other races.

High total bilirubin may be caused by:

  • Anemia
  • Cirrhosis
  • A reaction to a blood transfusion
  • Gilbert syndrome -- a common, inherited condition in which there is a deficiency of an enzyme that helps to break down bilirubin.
  • Viral hepatitis
  • A reaction to drugs
  • Alcoholic liver disease
  • Gallstones

Very strenuous exercise, such as marathon running, can increase your bilirubin levels.

Caffeine, penicillin, barbiturates, and nonsteroidal anti-inflammatory drugs (NSAIDs) called salicylates all lower your bilirubin levels.

Lower-than-normal levels of bilirubin aren’t a problem.

In newborns, high bilirubin levels that don’t level out in a few days to 2 weeks may be a sign of:

  • Blood type incompatibility between mother and child
  • Lack of oxygen
  • An inherited infection
  • A disease affecting the liver

Show Sources


American Association of Clinical Chemistry: “Bilirubin.”

Mayo Clinic: “Bilirubin Test.”

U.S. Department of Veterans Affairs: “Bilirubin.”

Johns Hopkins Medicine: “Hemolytic Anemia.”

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