Liver Function Test

What is a Liver Function Test?

The liver is an organ that removes contaminants and medicines from the blood and makes them harmless. It has several functions, including production of enzymes, proteins, blood clotting factors and bile, vitamin storage, and hormone and blood sugar regulation.

Liver function tests (also called LFTs or liver blood tests) investigate how well the liver is functioning, monitoring its overall health. They can detect whether there are or have been any abnormalities, such as cell damage or inflammation, occurring in the liver. Liver function tests measure the levels of the substances such as enzymes and proteins produced in the liver. The production, processing and/or release may be altered if the liver is abnormal, damaged, or diseased.

Buy a Liver Function Test

The liver function test includes return postage by Royal Mail 24 Tracked. Results are usually the same day the lab receives your sample. The full lab report is available to you, along with a doctor's interpretation of the results.

What are the main Liver Function Tests?

Substances measured in a liver function test may include:

• The enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (GGT), which are made by the liver. Some liver enzymes are found in tissues other than the liver and so can indicate diseases of tissues other than the liver
• Bilirubin (a waste product)
• The proteins albumin and globulin that are made in the liver, and the total protein in the blood.

Why is a Liver Function Test important?

By checking the overall health of the liver, liver function tests can help to detect and diagnose liver diseases, such as hepatitis, cirrhosis (liver scarring), and alcohol-related liver disease, and investigate symptoms of liver or other disorders. They can be used to monitor changes in liver function, liver or gallbladder disease, the effectiveness of treatment for liver disease, side effects of medicines that affect the liver, and medicine overdose. They can also provide screening for people with potential liver damage, such as those with a family history of liver disease or exposed to hepatitis, and heavy alcohol drinkers.

Who should monitor their Liver Function?

Liver function tests are used when symptoms indicate a liver condition, including jaundice (yellowy skin and eye whites), gastrointestinal problems, changes in urine and stool colour, and tiredness. Tests may also be done to monitor liver function, when taking certain medicines, if family members have liver disease, on exposure to hepatitis virus, or with excessive consistent alcohol intake.

How to test for Liver Function?

Several liver function tests may be carried out using one blood sample. The blood sample is sent to a laboratory for testing. If any of the liver function tests are abnormal, the results will help to determine your problem or more tests may be necessary to confirm or exclude a particular diagnosis.

Some food and medicines can affect levels of enzymes and proteins in the blood, and therefore affect the test results. If this is the case, then you may have to avoid these medicines or fast before the test.

What do Liver Function Test results indicate?

One abnormal result among the individual liver function tests may not indicate a problem with the liver, although two or more abnormal test results frequently indicate the problem or the need to investigate further.

Results indicating liver disease include:

• Increased ALT and AST indicate inflammation, liver scarring, and cell death, and fat accumulation in the liver
• ALP is increased in diseases or blockage of the bile duct and liver disease
• GGT is sensitive to medicine- and alcohol-related liver damage, and bile duct disorders
• Raised total bilirubin usually indicates liver disease or blockage of the bile duct from gall stones, but levels are altered during pregnancy
• Albumin can be low where there is major loss of liver tissue in chronic disease and inflammatory conditions
• Globulin (that helps fight infections) are low in liver disease and inflammatory conditions
• Raised total protein is commonly seen in hepatitis conditions

What is a normal Liver Function Test result?

Each laboratory has its own range of normal results (known as reference ranges). Your doctor at The Online Clinic will be able to tell you if you are within the local laboratory range or if your results indicate that you may have a liver condition.

How long does it take?

Once you place your order, we will send out the blood collection kit. This should arrive the next day. You then book your appointment with Superdrug (or attend our lab in London for a professional blood draw). A phlebotomist will take your blood sample, and then you send it back to us (with the pre-completed lab form we provide) in our reply paid envelope. The sample is normally in the lab the day after you send it back and then you will have your results the same day, along with an interpretation from a doctor.

How to maintain or achieve good Liver Function

You can help your liver to stay healthy by:

• Eating a healthy balanced diet and taking regular exercise
• Responsible alcohol drinking, by keeping to the weekly recommended units of alcohol, being aware of how much you drink, and avoiding too much at any one time
• Learning if your medicines could affect your liver.

Reviewed by: Dr Loraine Haslam MBBS, DRCOG, DFSRH, LoC SDI, LoC IUT, MRCGP
GMC registration number: 4524038
Date: 1 March 2024
Next review: 28 February 2026
All UK registered doctors can have their registration checked on
The Medical Register at the GMC website.