Bilirubin is a yellowish pigment that is made during the body's normal process of breaking down old red blood cells. It is processed by the liver to be removed from the body. If your liver is healthy only small amounts of bilirubin are found in blood but if your liver isn't working properly bilirubin levels rise. This can cause jaundice, a condition that causes your skin and the whites of the eyes to become yellow.
Measuring bilirubin levels in the blood is used to diagnose and monitor liver disorders and is part of the Liver Function Tests panel, a group of tests that measure different liver substances. These tests are all performed on the same blood sample and give information about how your liver is working.
Bilirubin tests are also performed on newborn babies to monitor jaundice. Bilirubin tests are also used to help diagnose and monitor haemolytic anaemia, a disorder in which red blood cells are destroyed faster than they can be made and more rarely, to help detect certain rare genetic disorders in sick babies.
Why get tested?
If you have symptoms such as jaundice and your doctor suspects a liver disorder, they will order a bilirubin test as part of a Liver Function Test panel.
A bilirubin test can help decide if your jaundice is due to a problem in the liver or a condition in which too many red blood cells are being broken down. This can be done by measuring two different chemical forms of bilirubin —conjugated (or direct) and unconjugated (or indirect) bilirubin.
|High conjugated bilirubin
|Possible causes include a blockage of the liver or bile duct, perhaps due to gallstones, hepatitis, trauma, a drug reaction, or long-term alcohol use
|High unconjugated bilirubin
|Haemolysis (breakdown of red blood cells)
This is a disorder in which red blood cells are destroyed faster than they can be made. This can be inherited (sickle cell anaemia and thalassemia) or acquired through a range of conditions such as infections, blood cancers, autoimmune disorders such as lupus, rheumatoid arthritis, or ulcerative colitis, and as a reaction to some medications.
Newborn or neonatal jaundice
Some babies are born with jaundice because their livers are not developed enough to get rid of bilirubin. It is not uncommon to see high bilirubin levels in babies typically two to seven days old. This is a temporary condition that usually resolves within a few days.
Haemolytic disease of the newborn
Newborn jaundice is likely to be of concern if it persists longer than 8 - 14 days and may be caused by abnormal metabolism in the liver or malformation of the bile ducts. A condition known as haemolytic disease of the newborn is when the newborn’s red blood cells are being destroyed due to a blood incompatibility between the baby and mother.
When levels of bilirubin are above a critical threshold, treatment such as phototherapy (special light therapy), blood exchange transfusion, and medications can be used to reduce it.
Although bilirubin may be toxic to brain development in newborns (up to the age of about two weeks), higher bilirubin levels in older children and adults do not pose the same threat. In older children and adults, the blood-brain barrier is more developed and prevents bilirubin from crossing into the brain cells. High bilirubin levels in children or adults, however, strongly suggest a medical condition that must be investigated and treated.
Having the test
Reading your test report
Your results will be presented along with those of your other tests on the same form. You will see separate columns or lines for each of these tests.
An elevated bilirubin result indicates jaundice and treatment will depend on the cause.
Your results will be compared to reference intervals (sometimes called a normal range).
If your results are flagged as high this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.
Bilirubin Reference Intervals
The reference intervals for this test are common reference intervals which means that most laboratories in Australia should be using this same target range.
Adult 1-20 µmol/L
Questions to ask your doctor
The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.
You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.
Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:
Any more to know?
Increases in bilirubin also may be due to metabolic problems, obstruction of the bile duct, infection, physical or chemical damage to the liver, or an inherited abnormality such as Gilbert's, Rotor's, Dubin-Johnson or Crigler-Najjar syndromes.
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