Test Overview

A bilirubin test measures the amount of
bilirubin in a blood sample. Bilirubin is a brownish yellow substance found in bile. It is produced when the liver breaks down old
red blood cells. Bilirubin is then removed from the body through the stool
(feces) and gives stool its normal color.

Bilirubin
circulates in the bloodstream in two forms:

  • Indirect (or unconjugated) bilirubin. This form of
    bilirubin does not dissolve in water (it is insoluble). Indirect bilirubin
    travels through the bloodstream to the liver, where it is changed into a
    soluble form (direct or conjugated).
  • Direct (or conjugated) bilirubin. Direct bilirubin
    dissolves in water (it is soluble) and is made by the liver from indirect
    bilirubin.

Total bilirubin and direct bilirubin levels are
measured directly in the blood, whereas indirect bilirubin levels are derived
from the total and direct bilirubin measurements.

When bilirubin
levels are high, the skin and whites of the eyes may appear yellow (jaundice). Jaundice may be caused by liver disease
(hepatitis), blood disorders (hemolytic anemia), or blockage of the tubes (bile ducts) that allow bile to pass
from the liver to the
small intestine
.

Mild jaundice in newborns usually does not cause problems. But too much bilirubin
(hyperbilirubinemia) in a newborn baby can cause brain
damage (kernicterus) and other serious problems. So some
babies who develop jaundice may need treatment to lower their bilirubin
levels.

Why It Is Done

The bilirubin test is used to:

  • Check liver function and watch for signs of
    liver disease, such as hepatitis or
    cirrhosis, or the effects of medicines that can damage
    the liver.
  • Find out if something is blocking the bile ducts. This
    may occur if
    gallstones, tumors of the pancreas, or other
    conditions are present.
  • Diagnose conditions that cause increased
    destruction of
    red blood cells, such as hemolytic anemia or
    hemolytic disease of the newborn.
  • Help
    make decisions about whether newborn babies with
    neonatal jaundice need treatment. These babies may
    need treatment with special lights, called phototherapy. In rare cases, blood
    transfusions may be needed.

How To Prepare

Adults should not eat or drink for 4
hours before a bilirubin test.

No special preparation is needed for
children before having a bilirubin test.

Tell your doctor if
you:

  • Are taking any medicines.
  • Are
    allergic to any medicines.
  • Are or might be pregnant.

Talk to your doctor about any concerns you
have regarding the need for the test, its risks, how it will be done, or what
the results will mean. To help you understand the importance of this test,
fill out the
medical test information form (What is a PDF document?).

How It Is Done

Blood sample from a heel stick

For a heel stick
blood sample, several drops of blood are collected from the heel of your baby.
The skin of the heel is first cleaned with alcohol and then punctured with a
small sterile lancet. Several drops of blood are collected in a small tube.
When enough blood has been collected, a gauze pad or cotton ball is placed over
the puncture site. Pressure is maintained on the puncture site briefly, and
then a small bandage is usually applied.

Instead of the standard
heel stick, some hospitals may use a device called a transcutaneous bilirubin
meter to check a newborn’s bilirubin level. This small handheld device measures
bilirubin levels when it is placed gently against the skin. With this device,
there may be no need to puncture the baby’s skin. This is a screening test, and
a blood sample will be needed if your baby’s bilirubin level is high.

Blood sample from a vein

The health professional
taking a sample of your blood will:

  • Wrap an elastic band around your upper arm to
    stop the flow of blood. This makes the veins below the band larger so it is
    easier to put a needle into the vein.
  • Clean the needle site with
    alcohol.
  • Put the needle into the vein. More than one needle stick
    may be needed.
  • Attach a tube to the needle to fill it with
    blood.
  • Remove the band from your arm when enough blood is
    collected.
  • Put a gauze pad or cotton ball over the needle site as
    the needle is removed.
  • Put pressure on the site and then put on a
    bandage.

How It Feels

Blood sample from a heel stick

A brief pain, like
a sting or a pinch, is usually felt when the lancet punctures the skin. Your
baby may feel a little discomfort with the skin puncture.

Blood sample from a vein

The blood sample is taken
from a vein in your arm. An elastic band is wrapped around your upper arm. It
may feel tight. You may feel nothing at all from the needle, or you may feel a
quick sting or pinch.

Risks

Heel stick

There is very little chance of a
problem from a heel stick. A small bruise may develop at the site.

Blood test

There is very little chance of a
problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You
    can lower the chance of bruising by keeping pressure on the site for several
    minutes.
  • In rare cases, the vein may become swollen after the blood
    sample is taken. This problem is called phlebitis. A warm compress can be used
    several times a day to treat this.

Results

A bilirubin test measures the amount of
bilirubin in a blood sample. The results are usually
available in 1 to 2 hours.

Normal values in adults

The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Bilirubin levels in adultsfootnote 1
Bilirubin typeBilirubin level

Total bilirubin

0.0-1.4
mg/dL or 1.7-20.5
mcmol/L

Direct bilirubin

0.0-0.3 mg/dL or 1.7-5.1 mcmol/L

Indirect bilirubin

0.2-1.2 mg/dL or 3.4-20.5 mcmol/L

High values

  • High levels of bilirubin in the blood may be
    caused by:

    • Some infections, such as an infected
      gallbladder, or
      cholecystitis.
    • Some inherited diseases,
      such as Gilbert’s syndrome, a condition that affects how the liver processes
      bilirubin. Although jaundice may occur in some people with Gilbert’s syndrome,
      the condition is not harmful.
    • Diseases that cause liver damage,
      such as
      hepatitis,
      cirrhosis, or
      mononucleosis.
    • Diseases that cause
      blockage of the bile ducts, such as
      gallstones or cancer of the
      pancreas.
    • Rapid destruction of
      red blood cells in the blood, such as from
      sickle cell disease or an
      allergic reaction to blood received during a
      transfusion (called a transfusion reaction).
    • Medicines that may increase bilirubin levels. This
      includes many antibiotics, some types of birth control pills, diazepam (Valium), flurazepam, indomethacin
      (Indocin), and phenytoin (Dilantin).

Low values

Low levels of bilirubin in the blood
may be caused by:

  • Medicines that may decrease bilirubin
    levels. This includes vitamin C, phenobarbital, and
    theophylline.

Normal values in newborns

Normal values in
newborns depend on the age of the baby in hours and whether the baby was
premature or full term. Normal values may vary from lab to lab.

What Affects the Test

Reasons you may not be able to
have the test or why the results may not be helpful (except in newborns)
include:

  • Caffeine, which can lower bilirubin
    levels.
  • Not eating for a long period (fasting), which normally
    increases indirect bilirubin levels.

What To Think About

  • Bilirubin can be measured in amniotic fluid if your
    doctor thinks that your unborn baby may have a condition that destroys red
    blood cells (erythroblastosis fetalis). For more information, see the topic
    Amniocentesis.
  • Bilirubin may also be measured in the urine in some cases. Normally, urine does
    not contain any bilirubin. If bilirubin is detected in urine, additional
    testing may be needed to determine the cause. High amounts of bilirubin in
    urine may indicate that the bilirubin is not being removed from the body by the
    liver.
  • Using a transcutaneous bilirubin test, doctors can screen
    all newborns for jaundice. They place a device gently against the skin to check
    bilirubin levels before a baby goes home from the hospital. For more information, see the topic Jaundice in Newborns.

References

Citations

  1. Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.

Other Works Consulted

  • Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.

Credits

ByHealthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD – Internal Medicine
Adam Husney, MD – Family Medicine
Martin J. Gabica, MD – Family Medicine
Specialist Medical Reviewer W. Thomas London, MD – Hepatology

Current as ofOctober 9, 2017