Serum Total Bilirubin

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

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 this test is required

A doctor usually requests a bilirubin test in conjunction with other laboratory tests (this usually includes ALP and ALT) as a group called liver function tests (LFTs). LFTs may be requested when a patient: shows evidence of jaundice has a history of drinking excessive amounts of alcohol has suspected drug toxicity or is taking medications that are metabolised by the liver or that can affect liver function has been exposed to hepatitis viruses is ill, to determine if the liver is affected and that, if needed, it is safe to give drugs metabolised by the liverOther signs and symptoms of liver disease that may prompt testing of LFTs include: dark, amber-coloured urine pale stools itching nausea and vomiting abdominal pain and/or swelling fatigue and general malaise

What the Test Detects

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…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. Normally the total bilirubin is measured in the laboratory. In some cases it may be useful to useful to separately measure conjugated and unconjugated bilirubin (also called a ‘split bilirubin’ measurement or ‘direct’ and ‘indirect’ bilirubin). See MoreSee Less

Preparation for the Test

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

Sample Requirements

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 a device on the skin called a transcutaneous bilirubin meter. This device is non-invasive, but in some situations it will need to be followed up by a blood test.

Additional Notes

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 into the brain. Elevated bilirubin in children or adults, however, strongly suggests an underlying disease 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.

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