Also Known As
LFTs
Liver panel
Hepatic function tests
Formal Name
Hepatic Function Panel
This article was last reviewed on
This article waslast modified on 17 July 2018.
At a Glance
Why Get Tested?

To screen for and monitor liver disease

When To Get Tested?

When you have symptoms of a liver disorder such as jaundice or have been exposed to substances that can cause liver damage such as a paracetamol overdose

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

None

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 will be able to access your results online.

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, gender, 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?

The liver is a large organ located in the upper right-hand part of the abdomen behind the lower ribs. It takes up drugs and toxic substances from the blood and renders them harmless. It produces proteins, including enzymes and blood clotting factors, helps maintain hormone balance and stores vitamins. The liver produces bile, a fluid that is transported through ducts to the gallbladder to be stored and then to the small intestine to help digest fats.

Liver disease is detected, evaluated and monitored by combinations of up to five tests measured at the same time on a blood sample. These may include:

  • Alanine aminotransferase (ALT) – an enzyme mainly found in the liver; the best test for detecting hepatitis
  • Aspartate aminotransferase (AST) – an enzyme found in the liver and a few other places, particularly the heart and other muscles in the body
  • Total bilirubin – measures all the yellow bilirubin pigment in the blood
  • Another test, conjugated bilirubin, measures the form made only in the liver and is often requested with total bilirubin in infants with jaundice
  • Alkaline phosphatase (ALP) – an enzyme related to the bile ducts; often increased when they are blocked, either inside or outside the liver
  • Albumin – measures the main protein made by the liver and tells how well the liver is making this protein
  • Total protein - measures albumin and all other proteins in blood, including antibodies made to help fight off infections

Other tests that can help to assess liver function include gamma-glutamyl transferase (GGT), 5’-nucleotidase (5’-NT) and prothrombin time (PT), together with bilirubin and urobilinogen in urine.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

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

No test preparation is needed.

Accordion Title
Common Questions
  • How is it used?

    Liver function tests are used to help determine the cause of symptoms such as jaundice that may be due to liver disease. They are also used to screen for potential liver damage, for example in alcoholics or people exposed to the hepatitis virus, and also to monitor changes in abnormal liver function.

  • When is it requested?

    These tests are used when symptoms suspicious of a liver condition are noticed. These include: jaundice, dark urine and light-coloured stools; nausea, vomiting and diarrhoea; loss of appetite; vomiting of blood; bloody or black stools; swelling or pain in the belly; unusual weight change; and fatigue or loss of stamina. One or more of these tests may be requested when a person has been or may have been exposed to a hepatitis virus; has a family history of liver disease; has excessive alcohol intake; or is taking a drug that can cause liver damage.

  • What does the test result mean?

    It is important to note that abnormal results in the individual tests can occur in conditions that do not involve the liver or the bile ducts and that, conversely, normal results can be found in patients with serious liver disease. However, one or more abnormal results often point to a diagnosis or to further investigations.

    • Raised alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values indicate leakage from cells due to inflammation or cell death. Liver disease is more likely when the values of AST and ALT are higher, ALT rising more than AST in acute liver damage such as hepatitis. When there is doubt about values, a raised creatine kinase (CK) will confirm muscle damage and measurement of troponin will show whether it is the heart that is damaged. Gamma-glutamyl transferase (GGT) seems to be more sensitive than ALT and AST for detecting liver damage from drugs and alcohol, and for detecting early rejection after liver transplantation.
    • A raised total bilirubin is usually due to liver disease or blockage of the passage of bile to the gut, for example by gall stones. Bilirubin is made water soluble (conjugated) by the liver and is then excreted in the urine, the stools becoming pale. However, a raised bilirubin can also occur in conditions where the breakdown of red blood cells produces more unconjugated bilirubin than the liver can handle, for example in newborn babies. If this is suspected, both total and conjugated bilirubin are measured and monitored.
    • Liver disease and blockage of the bile ducts also increase alkaline phosphatase (ALP). This is believed to be due to increased bile duct pressure causing the liver to make more ALP. If there are localised lesions within the liver, for example deposits of cancer cells, then ALP may be stimulated to rise but there may be sufficient normal liver around the deposits to keep bilirubin normal. Bone disease can also increase ALP. In patients with a normal bilirubin and a raised ALP, the measurement of 5’-nucleotidase (5’-NT) can help. It rises with liver ALP but is normal in bone disease.
    • Albumin is made only in the liver and may be low when there has been extensive loss of liver tissue in long-standing disease. Other causes of a low albumin include malnutrition (which may accompany alcoholic liver disease), kidney disease, due to loss of protein in the urine, and inflammatory conditions anywhere in the body when the liver switches to making other proteins.
    • Total protein is usually normal in liver disease. The difference between its concentration and that of albumin, called globulin, tends to increase when albumin falls, but very high values are seen most commonly in alcoholic hepatitis and in hepatitis caused by the body producing antibodies against its own liver (autoimmune hepatitis).
    • Patients with liver disease often bruise easily and cuts take a long time to stop bleeding. A long prothrombin time (PT) suggests a deficiency of clotting factors made by the liver or a deficiency of vitamin K which is needed for the factors to work. The deficiency can be the result of severe malnutrition, for example in alcoholism) or the result of blockage of bile passage to the gut. (Bile contains bile salts that are needed for the gut to absorb fat, and vitamin K is fat soluble.) Patients with a long PT may be given an injection of vitamin K and the PT measured again in 24 hours. A quicker PT after the injection indicates a deficiency of vitamin K rather than of clotting factors.
  • Is there anything else I should know?

    Depending on the history, examination and results of the liver function tests your doctor may request one or more further tests including alphafetoprotein, alpha-1 antitrypsin, CA 19-9, caeruloplasmin, copper, hepatitis virus antibodies A, B and C and smooth muscle antibody. Sometimes imaging scans are needed, and occasionally a small sample of liver is taken with a needle (biopsy) to be examined under a microscope.

  • Why does my doctor want to know what medicines I am taking?

    Many over-the-counter drugs and herbal or dietary supplements have the potential to affect the liver. Excessive paracetamol use and the combination of paracetamol and alcohol for instance can cause severe liver damage, as can exposure to toxins such as poisonous mushrooms.

  • Can I have liver disease if I feel fine?

    Yes, early liver disease often causes no symptoms or mild nonspecific symptoms, such as fatigue and nausea.

  • Can I have abnormal test results and not have liver disease?

    Yes, many conditions including shock, burns, severe infections, muscle trauma, muscle damage from severe exercise and pregnancy can cause one or more of the liver function tests to be abnormal. More conditions that can cause abnormal results are discussed under ‘What do the test results mean’.

  • Why is my family history important?

    Some liver conditions, such as haemochromatosis and Wilson's disease may be inherited. Early detection of these conditions allows them to be treated and managed appropriately.