About the Test
Purpose of the test
Doctors often order a bilirubin test along with other tests performed on a single blood or urine sample, such as in a comprehensive metabolic panel, a liver panel, or a urinalysis.
Testing bilirubin in the blood and urine can help doctors diagnose problems such as jaundice, a condition that may cause your eyes and skin to turn yellow, as well as hepatitis, cirrhosis, gallbladder disease, and hemolytic anemia.
Bilirubin blood testing is also used to diagnose newborn jaundice, which can lead to kernicterus at very high bilirubin levels. Prolonged and very high bilirubin levels can lead to complications if left untreated, so testing is commonly performed in newborns during their first few days of life and when signs of jaundice appear.
Repeated bilirubin testing can help a doctor monitor the disease’s status and how you respond to treatment if you have been diagnosed with a liver disorder.
What does the test measure?
The bilirubin blood test measures the amount of bilirubin in the blood. Results are commonly expressed as mg/dL, or milligrams of bilirubin per deciliter of blood (serum or plasma).
Bilirubin mainly exists in two forms in the blood. Initially, bilirubin is “unconjugated” and water-insoluble. Unconjugated bilirubin is attached to albumin, the main protein in blood that carries substances to the liver.
In the liver, bilirubin undergoes a process called conjugation with a substance called glucuronide; bilirubin becomes water-soluble and ready to be excreted into the bile.
A total blood test includes unconjugated and conjugated bilirubin. Due to the uniqueness of the analytical measurement of bilirubin, unconjugated bilirubin may also be called indirect bilirubin (total bilirubin minus direct bilirubin). At the same time, conjugated bilirubin may be referred to as direct bilirubin (directly measured).
Another less common measurement, delta bilirubin, is only formed when the excretion of conjugated bilirubin by the liver is impaired, like when a patient suffers from a bile duct obstruction. This type of conjugated bilirubin is linked to albumin and may persist for a prolonged period in your blood.
Neonatal bilirubin is commonly assessed in newborns and refers to the marked elevation of total bilirubin, mainly due to the increase in unconjugated bilirubin. Typically, a newborn’s liver needs a few days to take over the clearance of the bilirubin by conjugating bilirubin. This leads to increased bilirubin levels, gradually reaching normal levels about one week after birth.
The urinary bilirubin test measures whether or not bilirubin is present in the urine. For bilirubin to be present in urine, it has to be conjugated and water-soluble. If there is bilirubin present, urine may become tea or cola-colored.
Finding a Bilirubin Test
How can I get a bilirubin test?
Bilirubin testing is typically conducted in a medical setting after being ordered by a doctor.
If you are being evaluated for a liver condition or red blood cell disorder, your doctor may order other tests, including blood or urine tests, an ultrasound, or a biopsy.
Can I take the test at home?
At-home bilirubin blood testing is not available.
Some at-home urinalysis kits allow you to measure several parameters, including testing for bilirubin in your urine. These kits typically involve collecting a urine sample in a provided cup, then dipping a test strip in the cup, or using a pipette to add drops of urine to the test strip.
It is important to interpret any at-home bilirubin test results under the guidance of a doctor. If an at-home urine test indicates bilirubin in your blood, your doctor will likely want to repeat the urine test or conduct other follow-up testing to confirm the result.
How much does the test cost?
The price of a bilirubin test will vary depending on health insurance coverage, where you receive the test, and whether you are receiving additional tests ordered by your doctor. You may be responsible for out-of-pocket costs, including deductibles and copays.
Talk with your insurance company or health care provider to learn about the cost of bilirubin testing.
Taking a Bilirubin Test
A bilirubin blood test requires a sample of blood drawn from a vein in your arm. And a urinary bilirubin test requires a urine sample. You may be tested in a doctor’s office, lab, or medical clinic.
Before the test
If you are taking a bilirubin blood test, your doctor may ask you not to eat or drink for four hours before the test.
Many medications can interfere with bilirubin test results, so it’s important to tell your doctor about the medicines you take. Your doctor will explain whether you need to stop taking any medications before the bilirubin test, but don’t stop taking the medication without consulting your doctor first.
During the test
When you take a bilirubin blood test, a health care provider will use a small needle to draw a blood sample from a vein in your arm. You may feel a light prick or sting as the needle enters your arm. The blood draw itself should take no more than a few minutes. For infants, a small blood sample is taken from the baby’s heel instead.
During a urinary bilirubin test, you will be given a collection container and pointed to a private bathroom to collect a urine sample. Your health care provider might offer additional instructions on how to use the “clean catch” method for collecting a sterile “spot” urine sample. This involves washing your hands, cleaning your genital area, and urinating a small amount in the toilet before doing so into the collection container.
After the test
If you are asked not to eat or drink before a bilirubin blood test, you might bring a snack to eat after you finish your blood draw. You can resume your normal activities immediately following the blood test.
There may be slight bruising or pain around the needle’s insertion area. Any discomfort should go away quickly. Complications are rare, but if you notice excessive bleeding or signs of infection, let your doctor know.
There are no special precautions to take after a urinary bilirubin test.
Bilirubin Test Results
Receiving test results
A blood sample taken to measure bilirubin must be sent to a lab for analysis. It may take several days from giving your blood sample to receiving your test results.
A urine sample may be analyzed in your doctor’s office and/or sent to a laboratory for analysis. Your doctor will tell you when to expect the results of your urinary bilirubin test.
Interpreting test results
Bilirubin blood test results may indicate the total level in your blood. Some results may also list conjugated (direct) or unconjugated (indirect) bilirubin levels. These two levels typically add up to the total bilirubin level.
Your test results will also include reference ranges, the normal range of bilirubin levels. Results that fall outside the reference range, especially those above the upper normal level, may indicate the presence of disease or a need for further testing.
Reference ranges may vary depending on the lab that analyzes your blood sample and sends your results. The American Board of Internal Medicine uses the following reference ranges for adults:
- Total bilirubin: 0.3–1.0 mg/dL
- Direct bilirubin: 0.1–0.3 mg/dL
- Indirect bilirubin: 0.2–0.7 mg/dL
But these ranges are not universal. It is important to discuss your results with your health care provider, who will be in the best position to interpret what your results mean in the context of your overall health.
Infants commonly have higher bilirubin levels in the blood after birth as their livers continue to develop. As such, bilirubin testing is standard for all infants in their first 48 hours and is also often performed as a precautionary measure to monitor the change in these levels. If you are concerned about your baby’s bilirubin levels or if they are showing signs of jaundice, it is important to talk with your pediatrician.
A urinary bilirubin test result will either indicate a positive result, meaning it was detected in the urine (known as bilirubinuria), or a negative result, meaning bilirubin was not detected. If you are healthy with normal liver function, you should not have bilirubin in your urine.
Having a conversation with your doctor after you receive your results can help you understand what they mean and learn about the next steps for your care. You may find it helpful to ask these questions:
- What were the results of my bilirubin test? Are they normal or abnormal?
- Were any other measurements taken? What were the results?
- What do these tests tell us about my overall health?
- Do I need any follow-up tests?
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