Liver function tests (LFT) – basic information

A liver function test (LFT) is a blood test that measures the levels of several substances (enzymes and proteins) produced by your liver. This can give an indication of the condition of your liver.

This page is a short summary about liver function tests. For more detailed information, see Liver function tests (LFT) – in-depth.

What is a liver function test?

A liver function test (also called LFT) is a blood test that can provide information about how well your liver is working or if it is under stress. The test measures the levels of a number of proteins and enzymes produced by liver cells. The substances are released when liver cells are damaged or when the flow of bile through the liver is blocked. The pattern of abnormalities can give a clue as to the cause of the liver problem. 

When are liver function tests measured?

Liver function tests are usually performed to:

  • test for liver disease and give an indication of how severe the disease is
  • monitor somebody who is known to have liver disease
  • find out how well a treatment is working
  • monitor side effects if you are taking prescription or non-prescription medicines that can affect your liver function.
Causes of liver damage or inflammation 
  • Obesity
  • Alcohol
  • Infections such as hepatitis A, B or C
  • Gallstones
  • Certain medicines such as paracetamol, antibiotics or some poisons
  • Autoimmune diseases such as autoimmune hepatitis, primary biliary sclerosis or primary sclerosing cholangitis
  • Tumour or cancer
  • Injury or trauma
  • Genetic diseases such as haemochromatosis and Wilson’s disease

Read more about liver disease.

What does it mean if the result is abnormal?

Interpreting liver function test results is complicated and is best done in consultation with your healthcare team. They will know what is normal for you and how these results relate to your other signs and symptoms.

They are not perfect tests. Abnormal values can be found if you have other health conditions, not related to the liver. For some people with very severe liver disease the levels may be normal.

The most common causes for elevated liver function tests are alcohol consumption and fatty liver due to obesity.

Learn more

The following is further reading that gives you more information on having a blood test and the liver function tests. Be aware that websites from other countries may contain information that differs from NZ recommendations.

Blood test safety information Labtests, NZ
Liver function tests Patient Info, UK
Liver function tests  Australasian Association of Clinical Biochemists

Credits: Health Navigator Editorial Team. Reviewed By: Dr Jeremy Steinberg, FRNZCGP Last reviewed: 06 Dec 2021