Also Known As
Total bilirubin, conjugated or direct bilirubin, unconjugated or indirect bilirubin
Formal Name
This article was last reviewed on
This article waslast modified on 2 November 2020.
At a Glance
Why Get Tested?

To screen for, detect and monitor liver disorders and haemolytic anaemia. To monitor neonatal jaundice and help detect certain rare genetic disorders in sick babies.

When To Get Tested?

If your doctor thinks you have symptoms or signs of liver damage, liver disease, bile duct blockage, haemolytic anaemia or a liver-related metabolic problem. In sick babies with jaundice.

Sample Required?

In adults, a blood sample from a vein in the arm; in newborns, a blood sample from a heel-prick

Test Preparation Needed?

No test preparation is necessary. The blood sample should ideally be protected from bright light before analysis.

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

Bilirubin is an orange-yellow pigment, a waste product primarily produced by the normal breakdown of haem, which is a component of a protein called haemoglobin. Haemoglobin is found in red blood cells and gives them their characteristic red colour and is used to carry oxygen round the body. Bilirubin is ultimately processed by the liver to allow its elimination from the body. This test measures the amount of bilirubin in the blood to evaluate a person's liver function or to help diagnose anaemia caused by excessive red blood cell destruction.

The normal life-span of red blood cells in the circulation is 120 days. When they are broken down the haem is initially released from the haemoglobin and then converted to unconjugated bilirubin. The unconjugated bilirubin is not water-soluble so it is carried by proteins in the blood to the liver. Within the liver, the unconjugated bilirubin has sugars attached to form water soluble conjugated bilirubin. This is secreted into bile and carried to the intestine where bacteria break it down, eventually producing the brown pigment that colours normal stools.

A small amount (approximately 250 to 350 milligrams) of bilirubin is produced daily in a normal, healthy adult. Normally, small amounts of unconjugated bilirubin are found in the blood, but virtually no conjugated bilirubin is present. Both forms can be measured by the laboratory tests but total bilirubin result (a sum of these) is usually reported.

How is the sample collected for testing?

In adults, blood is collected by needle from a vein in the arm. In newborns, a few drops of blood are usually collected from a heel-prick. Sometimes in newborns bilirubin is estimated by placing an instrument on the skin (a transcutaneous bilirubin meter).

Is any test preparation needed to ensure the quality of the sample?

No test preparation is necessary. The blood sample should ideally be protected from bright light before analysis.

Accordion Title
Common Questions
  • How is it used?

    When bilirubin concentrations in the blood increase it leads to a condition called jaundice (yellowing of the skin and/or the whites of the eyes). Further testing is often needed to help doctors find out the cause of the high bilirubin. Too much bilirubin may mean that too many red blood cells are being destroyed or liver damage is present.

    It is not uncommon to see high unconjugated bilirubin concentrations in newborn babies from the second to the seventh day of life. This transient condition is called physiological jaundice. Bilirubin concentrations rarely peak higher than five times the upper limit of normal. Up to 50% of full-term newborns and an even greater percentage of pre-term babies may have jaundice. The newborn’s liver is not fully mature and is unable to process bilirubin fast enough. Physiological jaundice is not abnormal and resolves within a few days.

    Newborn jaundice is likely to be abnormal if it persists longer than 8 - 14 days, when it could be caused by abnormal metabolism in the liver or malformation of the bile ducts. If the jaundice is present at birth and is caused by an elevated unconjugated bilirubin concentration, the newborns’ red blood cells may be being destroyed because of blood incompatibility between the baby and mother, called haemolytic disease of the newborn.

    In adults or older children, bilirubin is measured to diagnose and monitor liver diseases such as cirrhosis, hepatitis, or gallstones. Patients with sickle cell disease or other causes of haemolytic anaemia may have episodes where excessive red blood cell destruction takes place, increasing bilirubin concentrations in the blood.

  • When is it requested?

    A doctor usually requests a bilirubin test in conjunction with other laboratory tests including ALP, AST and ALT as a group called liver function tests (LFTs) when a patient has a history, signs or symptoms suggesting abnormal liver function. LFTs may be requested when a patient:

    • shows evidence of jaundice
    • has a history of drinking excessive amounts of alcohol
    • has suspected drug toxicity
    • has been exposed to hepatitis viruses

    Other signs and symptoms that may be present include:

    • dark, amber-coloured urine
    • pale stools
    • itching
    • nausea and vomiting
    • abdominal pain and/or swelling
    • fatigue and general malaise
  • What does the test result mean?

    Adults and children: Bilirubin concentrations can be used to identify liver disease or to monitor the progression of jaundice. Increased total or unconjugated bilirubin may be a result of haemolytic, sickle cell or pernicious anaemias or a transfusion reaction. If conjugated bilirubin is elevated, there may be some kind of blockage of the liver or bile ducts, hepatitis, trauma to the liver, cirrhosis, a drug reaction, or long-term alcohol abuse.

    Newborns: Excessive unconjugated bilirubin damages developing brain cells in infants (kernicterus) and may cause mental retardation, hearing loss, speech difficulties or fits. It is important that bilirubin concentrations in newborns do not get too high. When the concentration of unconjugated bilirubin is greater than 15 times the upper limit of normal, special treatment is used to reduce it: exposure of the skin to blue light and sometimes exchange blood transfusion.

    An excessive unconjugated bilirubin concentration may result from the breakdown of red blood cells due to blood typing incompatibility between the mother and her infant. For example, if the mother is Rhesus negative and the foetus inherits the father’s Rhesus positive trait, foetal red blood cells may cross the placenta into the mother’s blood and she may develop antibodies which cross back into the foetus and cause haemolysis of the foetal Rh-positive red blood cells, resulting in excessively elevated unconjugated bilirubin.

    Determining conjugated and unconjugated bilirubin concentrations in newborns with jaundice is standard medical care. Malformation of the bile ducts (biliary atresia) obstructs the flow of bile, damaging the liver and causing raised concentrations of conjugated bilirubin. The condition requires early surgical treatment to avoid the need for liver transplantation.

  • Is there anything else I should know?

    Although unconjugated bilirubin may be toxic to brain development in newborns (up to the age of about 2–4 weeks), high bilirubin concentrations in older children and adults does not pose the same threat. In older children and adults, the 'blood-brain barrier' is more developed and prevents bilirubin from crossing this barrier to the brain cells. Elevated bilirubin in children or adults, however, strongly suggests a medical condition that must be investigated and treated.

    Bilirubin is not normally present in the urine. However, conjugated bilirubin is water-soluble and therefore may be excreted from the body in the urine when concentrations increase in the blood. Its presence in the urine usually indicates blockage of liver or bile ducts, hepatitis or some other liver damage. The most common method for detecting urine bilirubin is using the dipstick test that is part of urinalysis.

  • Are some people at more genetic risk of abnormal bilirubin levels than others?

    Several inherited conditions including Gilbert’s syndrome, Dubin-Johnson syndrome, Rotor’s syndrome, and Crigler-Najjar syndrome can cause a raised bilirubin concentration. Of these four syndromes the rarest, Crigler-Najjar is the most serious. The first three are usually mild, long-term conditions that can be aggravated under certain conditions, but in general cause no significant health problems. Gilbert's syndrome is relatively common (may effect up to 5% of the population) causes a small increase in bilirubin, but no clinical problems other than having to be excluded as a reason for very mild jaundice. Prolonged fasting or general illness can cause mild jaundice in subjects with Gilbert's syndrome.

  • How do you treat abnormal bilirubin levels and/or jaundice?

    Treatment depends on the cause of the jaundice. In newborns, bilirubin levels can be reduced using phototherapy (blue light therapy) and sometimes blood exchange transfusion. Drugs can also be used to reduce the bilirubin concentration. In Gilbert’s, Rotor’s, and Dubin-Johnson syndrome, no treatment is usually necessary. Crigler-Najjar syndrome requires blue light treatment throughout life, may respond to drug therapy or may require liver transplantation. Jaundice caused by an obstruction, for example gallstones, is often resolved by surgery to remove the blockage. Jaundice due to cirrhosis is often a result of long-term alcohol abuse and may not respond well to any type of therapy, although to stop drinking alcohol and to increase the consumption of nutritional food may improve the situation if the liver has not been damaged too badly.

  • Is there anything I can do to maintain healthy bilirubin levels?

    While there is no one specific thing, it is clear that excessive and long-term alcohol consumption can lead to cirrhosis and a permanently damaged liver. Avoiding excessive alcohol consumption, drug toxicity and eating a balanced, nutritional diet can help sustain a healthy liver.