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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 colour.
Bilirubin circulates in the bloodstream in two forms:
This form doesn't 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 bilirubin dissolves in water. (It is soluble.) It's made by the liver from indirect bilirubin.
Total bilirubin and direct bilirubin levels are measured directly in the blood. 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 look 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 doesn't 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.
The bilirubin test is used to:
For a heel stick blood sample, several drops of blood are collected from the baby's heel. 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. 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 hand-held 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 the baby's bilirubin level is high.
A health professional uses a needle to take a blood sample, usually from the arm.
The test will take a few minutes.
A brief pain, like a sting or a pinch, is usually felt when the lancet punctures the skin. A baby may feel a little discomfort with the skin puncture.
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little risk of a problem from a heel stick. Your baby may get a small bruise at the puncture site.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
The results are usually available in 1 to 2 hours.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
Low levels of bilirubin in the blood may be caused by:
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.
Current as of: September 8, 2022
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineMartin J. Gabica MD - Family MedicineW. Thomas London MD - Hepatology
Current as of: September 8, 2022
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Martin J. Gabica MD - Family Medicine & W. Thomas London MD - Hepatology
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