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.
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
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.
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
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
- 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
red blood cells, such as hemolytic anemia or
hemolytic disease of the newborn.
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.