Bilirubin Blood Test

What is a bilirubin blood test?

A bilirubin blood test measures the levels of bilirubin in your blood. Bilirubin is a yellowish substance made during your body's normal process of breaking down old red blood cells. Bilirubin is found in bile, a fluid your liver makes to help you digest food.

If your liver is healthy, it will remove most of the bilirubin from your body through your bile ducts (the tubes that carry bile from your liver). If your liver is damaged or your bile ducts are blocked, bilirubin can leak out of your liver and into your blood. When too much bilirubin gets into the bloodstream, it can cause jaundice, a condition that causes your skin and eyes to turn yellow. If you have jaundice, your health care provider may order a bilirubin blood test to check for liver disease or damage.

Bilirubin is usually tested with a blood test but can also be tested in your urine.

Other names: Total serum bilirubin, TSB total bilirubin, TBIL neonatal bilirubin, direct bilirubin, conjugated bilirubin, indirect bilirubin, unconjugated bilirubin

What is it used for?

A bilirubin blood test may be used to check the health of your liver, look for the cause of jaundice, or determine how well a treatment is working.

The test is also commonly used to help diagnose newborn jaundice. Many healthy babies get jaundice because their livers haven't developed enough to get rid of the bilirubin. Newborn jaundice is usually not harmful and clears up within a few weeks. But in some cases, high bilirubin levels can lead to brain damage, so infants are often tested as a precaution.

Why do I need a bilirubin blood test?

Your health care provider may order a bilirubin blood test:

• If you have symptoms such as jaundice, dark urine, clay-colored stool (poop),  or stomach pain. These could indicate hepatitis, cirrhosis, or other liver diseases.
• To find out if there is a blockage in your bile ducts.
• To monitor an existing liver disease.
• To diagnose disorders related to your body breaking down red blood cells too quickly. For example, high bilirubin levels in the bloodstream may be a sign of hemolytic anemia. This condition happens when your body destroys red blood cells faster than it makes them.

What happens during a bilirubin blood test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

If the test is done on your newborn, they will have a heel stick test. A health care professional will clean your baby's heel with alcohol and poke the heel with a small needle. They will collect a few drops of blood and put a bandage on the site.

Will I need to do anything to prepare for the test?

Your provider may tell you to fast (not eat or drink) for several hours before your blood test. You may need to stop taking certain medicines before this test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to. Your provider will let you know if there are any other special instructions.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

The results will show if the amount of bilirubin in your is in the normal range. The normal ranges can vary from lab to lab.

If the results are outside your lab's reference range, you may need further testing. Normal results can vary based on the lab, your sex, and if the test is being done on an infant or child. but high bilirubin levels may mean your liver isn't working right.

High bilirubin levels (hyperbilirubinemia) may be due to:

• Hemolytic anemia
• Liver disease
• Blockage in your bile ducts

Low bilirubin levels (hypobilirubinemia) are not usually a cause for concern but may be due to:

• Medicines such as antibiotics, birth control pills, sleeping pills, and seizure medicines 

Abnormal results don't always mean you have a medical condition that needs treatment. Higher-than-normal bilirubin levels can also be caused by some medicines, certain foods, or strenuous exercise. To learn what your results mean, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a bilirubin blood test?

A bilirubin blood test is only one measure of your liver health. If your provider thinks you might have a liver disease or a red blood cell disorder, you may need other tests, such as:

• Liver function tests, a group of tests that measure different substances in your blood
• Liver protein tests
• Urine tests
• An ultrasound
• A liver biopsy, to get a sample of your liver tissue to examine under a microscope