Bilirubin

Other names: Neonatal Bilirubin; Direct Bilirubin (Conjugated Bilirubin); Total Bilirubin; Indirect Bilirubin (Unconjugated Bilirubin)

Bilirubin is the yellow pigment located in bile. Bile is a thick liquid which is made by the liver; it helps to break down fats. When the red blood cells break down (they do this every 120 days and new cells replace them) the haemoglobin component is converted into unconjugated bilirubin; this is then taken to the liver, where it is attached to sugars, which make it soluble in water, which is called conjugated bilirubin. Conjugated bilirubin is placed into the bile by the liver and is broken down by bacteria in the small intestine; once it has been broken down it will then be excreted in the faeces (the brown colour of faeces is determined by the products of breaking down bilirubin). Around 85 percent of the bilirubin in the human body is formed by the degradation of red blood cells; the remaining 15 percent is made by the bone marrow and liver.

Why is the test used?

The test is used to measure the levels of bilirubin in the blood; the test is usually used to test for liver disorders or to monitor the condition of a patient who has already been diagnosed with a liver disorder.

The test is usually ordered for those who have symptoms of liver damage, liver disease or liver disorders; symptoms include:

  • Jaundice
  • Weakness
  • Tiredness
  • Dark urine
  • Nausea and vomiting
  • Abdominal pain

The test may also be ordered for those who are at high risk of developing a liver disorder, including those with a family history of live problems and those who drink heavily.

How is the test done?

The test is done using a sample of blood, which is usually collected from a vein in the arm. In infants, a sample is taken by pricking the heel and collecting the blood. Once the sample has been collected, it will be bottled, labelled and then sent away for analysis in the laboratory.

What do the results show?

If levels of bilirubin are higher than normal, this may indicate problems with the liver. If levels of total or unconjugated bilirubin are high, this may be caused by pernicious or sickle cell anaemia. If levels of conjugated bilirubin are high, this may indicate that the patient has hepatitis, liver cirrhosis or a blocked bile duct; elevated levels may also be symptomatic of long-term heavy drinking, a reaction to a drug or injury or damage to the liver.

In newborn babies, jaundice is fairly common and may not cause any problems; however, excessive levels of bilirubin can be very dangerous and can contribute to long-term problems and retarded growth. If levels are very high, treatment will be administered very quickly and further tests will be carried out to monitor the efficacy of the treatment.

Specific Blood Tests

Blood Test Guide

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