What Is a Bilirubin Test?

What to expect when undergoing this test

Bilirubin tests, which measure the levels of total bilirubin and direct bilirubin in your blood, are a group of blood tests that are used to help evaluate a variety of gastrointestinal and blood diseases.

Bilirubin is a chemical component inside red blood cells (RBCs). It has a yellowish brown color that contributes to the color of urine and stool. High levels of bilirubin can cause yellowing of the skin and eyes. Elevated bilirubin is harmful to the body, and it is an indication of several serious medical conditions.

Purpose of Test

You may need to have bilirubin tests to help with diagnosing an illness if you have signs, symptoms, or risk factors of liver disease, pancreatic disease, gallbladder disease, or hemolytic anemia (excessive break down of RBCs). Bilirubin tests are often also necessary for monitoring treatment if you have been diagnosed with any of these medical conditions. 

You may need a bilirubin test if you have:

The Danger of Too-High Bilirubin

Why This Test

The types of bilirubin measured by bilirubin tests can help your doctors identify whether you have a problem with excessive breakdown of your RBCs or with detoxifying bilirubin after your RBCs break down. Understanding how bilirubin normally acts in your body can help you understand why your doctors would order bilirubin tests for you. 

Typically, your RBCs carry oxygen and nutrients to provide you with energy. RBCs typically survive for about three to four months, and then they break down and some of their components are recycled. Indirect bilirubin is a toxic breakdown product of RBCs that needs to be detoxified in your liver through a process that changes it to direct bilirubin, which is then transported to your intestines through your bile ducts and gallbladder, and eventually excreted in the stool. 

A problem with any step of this process can cause you to have high bilirubin levels. If you have excessive breakdown of your RBCs, you will have low energy, possibly dark or bloody urine, your indirect bilirubin will be elevated, and your total bilirubin may also be elevated.

Potential Causes

  • If you have a disease that affects your gallbladder or bile ducts, which are connected to your liver, you may have nausea, vomiting, and stomach aches. You can have elevated direct bilirubin and possibly elevated total bilirubin too because you can’t eliminate them from your body.
  • If you have liver disease, you can have low energy, confusion, abdominal pain, and elevated direct bilirubin and/or indirect bilirubin and total bilirubin.

Because bilirubin levels are indicative of several different conditions, you will probably also need other tests at the same time to help sort out the cause of your symptoms.

Other Tests/Similar Tests

If you are having your bilirubin levels checked, there is a strong chance that your doctors will also check some other liver function tests or measures of your RBC concentration and function.

These additional tests, when considered along with the results of your bilirubin tests, provide a more complete picture of the cause and effects of your condition, helping in your diagnosis.

  • RBC counts: This test measures the concentration and quantity of your RBCs, and can identify if you have anemia. 
  • Hemoglobin: This blood test measures the level of hemoglobin, a protein that carries oxygen in your RBCs. 
  • Urine bilirubin levels: If you are having your blood bilirubin tested, you may also have a urine bilirubin test as well. This is not considered as accurate as a blood test, but it can help identify whether excess bilirubin is being eliminated in your urine. 
  • Alanine aminotransferase (ALT) and aspartate phosphatase (AST): These tests measure enzymes in the liver, and elevated levels are suggestive of liver injury or disease, which can be caused by drugs, alcohol, hepatitis, or trauma. 
  • Albumin: Low levels of albumin, a protein produced by the liver, suggest that the liver is not functioning as it should. 
  • Alkaline phosphatase (ALP): This is an enzyme that may be elevated with bile duct disease. 
  • Gamma Glutamyl Transferase (GGT): This is an enzyme that can become elevated with mild or early liver disease. If you have high levels, this suggests that your symptoms and bilirubin levels are more likely caused by liver disease than by hemolytic anemia. 
  • Infectious hepatitis tests: Liver disease can be caused by hepatitis A, B, C, D, and E, which are different hepatitis viruses that target the liver. These viruses spread from person to person through different mechanisms, and while they all harm the liver, they each typically have their own unique symptoms. 
  • Cholesterol and triglycerides: Cholesterol and fat levels can be abnormal with some liver diseases, so your doctor may also order cholesterol and triglycerides (a type of fat) at the same time as your bilirubin tests. 

Limitations

As you can tell based on the number of tests that may accompany bilirubin tests, the results are helpful but are they generally most helpful when considered along with other tests.

Risks and Contraindications

Bilirubin levels are measured with a blood test. The test itself is safe, without any side effects or contraindications.

Before the Test

If your doctor recommends that you have a bilirubin test, you may be able to have it right away at your doctor’s office or in a nearby laboratory. However, some labs require that you abstain from food or drink for up to eight hours before a bilirubin test, especially if you are also having your cholesterol level checked. This means that you may need to come back at another time to have your bilirubin test. It is best to check with your doctor or with the lab. 

Timing

A bilirubin test and any other blood tests you are having at the same time should take no longer than five minutes. The whole process, including checking in, signing consent forms, paying, and waiting for your turn can take a total of one to two hours. You can check with the lab where you will have your blood drawn to get a more precise estimate of how much time you should allot for your test. 

Location

Blood tests such as bilirubin levels can usually be done right in the doctor’s office. You may need to have your blood drawn at a hospital or laboratory, depending on the specifications and policies of your health insurance plan. 

What to Wear

Be sure that you either wear short sleeves or a shirt with sleeves that are loose enough to be easily pulled up above your elbow so that your vein can be easily accessed. Some people prefer to wear long sleeves if going to work, to avoid showing an obvious bandage. 

Food and Drink

You may need to abstain from food and drink for four to eight hours before your test. Be sure to check with your doctor. 

Cost and Health Insurance

A bilirubin test is usually covered by most health insurance plans. It is best to check with your insurance plan or with the lab where you will have your test done, just to be sure. It is also a good idea to check whether you are required to cover the cost of copay for this test. 

If you will be paying for the test yourself, the cost of a total blood bilirubin test with a direct blood bilirubin test ranges from approximately $20 to $90. You will not have a separate test to measure indirect bilirubin because that is calculated using the results of the total and direct bilirubin levels. As with most tests, the cost may be higher or lower, and you can find out the price from the lab or doctor’s office where you will have your test done. 

What to Bring

Be sure to bring a method of identification, your health insurance card, and a form of payment if you will need to cover the cost of copay or if you are paying for the test yourself. It is not necessary to bring anyone with you because you will be alert throughout the test and you can drive yourself to wherever you need to go afterward. If you are fasting from food in preparation for your test, it is a good idea to bring a snack or drink so that you won’t be hungry afterward.

During the Test

When you go to have your blood test, you will meet with a nurse or a phlebotomist (a technician who is specialized in drawing blood). 

Pre-Test

Right before your test, you will need to check in, sign consent for the test, and sign consent for payment. 

Throughout the Test

When you are about to have your test, you will meet your nurse or phlebotomist, who may ask you which hand you write with. You will likely have your blood drawn from the arm you do not write with.

He or she will look at your veins, will clean the area with an alcohol pad, and will tie an elastic band above your elbow to make your veins more visible and easier to access. You will feel a tiny pinch as the needle is inserted, and blood will rapidly enter into a tube. You can expect this to take less than a minute, and the needle will then be taken out.

You may be asked to hold down a cotton ball or gauze at the puncture site until bleeding stops, which should take less than a minute. Your phlebotomist or nurse will place a bandage over the tiny wound. 

Post-Test

You should be able to leave shortly after your test, as long as you are not bleeding. You can continue with your day without limitations.

After the Test

After your test you may experience mild soreness at the puncture site for a few hours. You might need to change to a fresh bandage once or twice over the first 24–36 hours after your blood test. If you have a puncture site that is visible, you should keep it covered to prevent an infection. 

If you continue to experience bleeding, if you develop a fever, or if you have pain in your arm or hand, you should call your doctor’s office. This is extremely uncommon and may be a sign of a bleeding disorder or an infection.

Interpreting Results

The results of your blood test should be ready within about a week. They will be reported as total bilirubin and direct bilirubin, and there may be a value for indirect bilirubin as well, which is calculated by subtracting the measured direct bilirubin from the measured total bilirubin.

Direct bilirubin is considered a good estimate of conjugated bilirubin, which is the form that is excreted in the feces. Indirect bilirubin is considered a good estimate of unconjugated bilirubin, which is the form that needs to be detoxified.

Total Bilirubin

  • The normal range is 0.3 to 1.2 mg/dL

Direct Bilirubin

  • The normal range is 0 to 0.3 mg/dL

Elevated levels of total bilirubin suggest liver disease, hemolytic anemia, pancreatitis, gallbladder disease, or bile duct disease. Elevated levels of direct bilirubin can occur with hemolytic anemia or with liver disease, such as alcoholic cirrhosis, hepatitis.

Low levels of bilirubin have not been considered problematic, although recent studies suggest that low bilirubin may be an indicator of poor health, especially among the elderly.

Follow-Up

If your bilirubin tests are abnormal, you may need additional blood tests, such as testing for hemolytic anemia or hepatitis infection, if you have not already had that done.

Depending on your test results and symptoms, you may also need to have follow-up imaging tests to assess your liver, gallbladder, or pancreas. For example, if you are a heavy drinker, your doctor may be concerned about pancreatitis or cancer of the liver. 

Possible Follow-Up Tests

  • Imaging tests: An abdominal ultrasound, computerized topography (CT), or magnetic resonance imaging (MRI) study can identify abnormalities in the liver and the surrounding structures, such as the pancreas, bile ducts, and gallbladder. 
  • Interventional testing: You may need more interventional testing than imaging tests, particularly if there is concern that you could have obstruction of your bile ducts or colon. Tests that can assess your digestive system from the inside include a colonoscopy or an endoscopy. 
  • Biopsy: If there is a suspicion that cancer could be the root of your symptoms, or if it is unclear what is causing your symptoms, then a biopsy, which is a sample of tissue, may be needed to help direct your treatment.

Repeating the Test

If you are being treated for liver, pancreas, bile duct, or gallbladder disease, you may need to have your tests repeated after a few months to assess whether your treatment is working. 

If you have hemolytic anemia, your condition is more accurately followed by repeated your hemoglobin levels and RBC count than by bilirubin levels. 

If you are at risk of liver disease, due to chemotherapy or alcohol intake, for example, you may need to have your bilirubin levels repeated periodically to reevaluate your condition.

A Word From Verywell

Bilirubin tests are helpful in diagnosing and following the progression of a number of medical conditions. If you need to have bilirubin tests, there is a strong chance that you need to have other tests as well. Some of the medical problems that cause abnormal bilirubin levels can be treated, but many of the causes can only be managed, which means that you may need to have your bilirubin levels rechecked periodically as your treatment continues.

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Article Sources
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  • Ngashangva L, Bachu V, Goswami P. Development of new methods for determination of bilirubin. J Pharm Biomed Anal. 2018 Sep 18;162:272-285. DOI: 10.1016/j.jpba.2018.09.034.