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Overview

What Is a Bilirubin Blood Test?

Bilirubin is a yellow substance produced when red blood cells break down. A bilirubin blood test measures the amount of bilirubin in a blood sample, usually reporting total bilirubin and sometimes direct, or conjugated, bilirubin. The results can provide information about liver function and how the body is breaking down red blood cells.

A clinician may order a bilirubin blood test by itself or as part of a liver function panel. This blood test is different from bilirubin testing in urine, which checks whether bilirubin is being released into the urine. The type of test used depends on the symptoms and the clinical question.

When It Is Needed

When Is a Bilirubin Blood Test Needed?

A clinician may recommend a bilirubin blood test when someone has yellowing of the skin or eyes, dark urine, pale stools, abdominal discomfort, nausea, or unusual tiredness. Testing can help evaluate possible liver, gallbladder, or bile duct problems and investigate high bilirubin causes. It may also be used when an examination or other blood test suggests elevated bilirubin or a problem affecting red blood cells.

  • Suspected liver, gallbladder, or bile duct disease
  • Symptoms or signs of jaundice
  • Possible increased breakdown of red blood cells
  • Monitoring a known liver condition or treatment
  • Evaluating jaundice in a newborn
  • Following up on an abnormal liver panel

Preparation

How to Prepare for a Bilirubin Blood Test

Many bilirubin blood tests do not require special preparation. However, the laboratory or clinician may ask you to fast if the test is combined with other blood tests. Ask what applies to your appointment, and do not assume that fasting is needed unless you receive that instruction.

During the Test

What Happens During a Bilirubin Blood Test?

A bilirubin blood test is usually a single, brief blood draw from a vein, commonly in the arm. A healthcare professional cleans the skin, places a needle into the vein, and collects blood in a tube. The needle is then removed, and pressure and a bandage are applied. The sample is sent to a laboratory for analysis.

Blood collection in newborns and infants

For a newborn or young infant, bilirubin may be collected using a small heel-stick sample when clinically appropriate. During the procedure, you may feel brief stinging or pressure, and a small bruise can develop afterward. Results are reported after the laboratory measures the bilirubin levels.

Risks

What Are the Risks of a Bilirubin Blood Test?

  • Brief pain or stinging when the needle is inserted.
  • Mild bruising, soreness, or bleeding at the puncture site.
  • Lightheadedness or fainting during or shortly after the draw.
  • Rare infection or bleeding that does not stop with pressure; serious complications are uncommon.

Results

Understanding Bilirubin Blood Test Results

A report may show total bilirubin and direct, or conjugated, bilirubin. Indirect bilirubin may be reported separately or calculated from the other values. Use the reference range printed by the laboratory because bilirubin normal range values can vary by laboratory, age, and clinical context. A clinician considers bilirubin total, bilirubin direct, symptoms, and other test results together.

Normal, high, and low bilirubin results

FindingWhat it may meanPossible next step
Within the laboratory rangeNo bilirubin abnormality is identified by that measurementInterpret alongside symptoms and other test results
Elevated bilirubinMay reflect liver or bile flow problems, increased red blood cell breakdown, or a benign patternClinician may review direct and indirect fractions and order follow-up tests
Low bilirubinUsually is not a sign of a serious problem by itselfInterpret with the rest of the blood test and clinical history

When to seek care

Abnormal results need clinical context

Contact a healthcare professional promptly about rapidly worsening yellow skin or eyes, confusion, severe abdominal pain, fever, vomiting, or very dark urine. Do not use one bilirubin value alone to decide whether a level is dangerous; the clinician determines urgency from the full clinical picture.

Diseases & Conditions

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