Also Known As
Gamma-glutamyl transferase
Formal Name
Gamma-Glutamyl transferase
This article was last reviewed on
This article waslast modified on 27 July 2018.
At a Glance
Why Get Tested?

To screen for liver disease or alcohol abuse; and to help your doctor tell whether a raised concentration of alkaline phosphatase (ALP) in the bloodstream is due to liver or bone disease

When To Get Tested?

If your doctor thinks that you have symptoms of a liver disorder/disease

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

None required

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?

Gamma-glutamyl transferase (GGT) is an enzyme found mainly in the liver. When the liver is injured or the flow of bile is obstructed, the concentration of GGT within the bloodstream rises. It is therefore a useful marker for detecting bile duct problems.

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?

    The GGT test helps to detect liver disease and bile duct injury. Doctors can also use the test to help find out the reason for a raised concentration of alkaline phosphatase (ALP) within the bloodstream. Both ALP and GGT are elevated in disease of the bile ducts and in some liver diseases, but only ALP will be elevated in bone disease. If the GGT concentration is normal in a person with a high ALP result, the cause is most likely to be bone disease. GGT can also be used to screen for alcohol abuse (it will be elevated in about 75% of long-term drinkers).

  • When is it requested?

    A doctor usually requests GGT along with other tests to evaluate a person who has signs or symptoms that suggest liver disease. Some of the symptoms of liver injury include jaundice, nausea, vomiting, abdominal (around the stomach area) swelling, abdominal pain, pruritus (severe itching), and tiredness.

    GGT is increased in most diseases that cause damage to the liver or bile ducts, but is usually not helpful in distinguishing between different causes of liver damage as a single test. However there are studies that indicate GGT can be used together with other markers as diagnostic scores to predict the presence of liver fibrosis and also for non-alcoholic fatty liver disease. GGT is also useful in determining the cause of a high ALP. In people with a history of alcohol abuse who are undergoing treatment, GGT may be used to check that the person is following the treatment program properly.

  • What does the test result mean?

    Your doctor is not usually concerned with low or normal results, but they do tell him/her that it is unlikely that you have liver disease.

    Raised GGT concentrations indicate that something is going on with your liver but not specifically what. In general, the higher the result the greater the damage to your liver. Elevated concentrations may be due to liver disease, but they may also be due to congestive heart failure, drinking alcohol, and use of many prescription and non-prescription drugs including nonsteroidal anti-inflammatory drugs (NSAIDs), lipid-lowering drugs, antibiotics, histamine blockers (used to treat excess stomach acid production), antifungal agents, anticonvulsants (seizure control medications), antidepressants, and hormones such as testosterone. Oral contraceptives (birth control pills) and clofibrate can decrease GGT concentrations.

  • Is there anything else I should know?

    Alcohol consumed within 24 hours of your GGT test may cause a temporary increase in the GGT result, if you consume alcohol regularly. If this occurs, your doctor may want to repeat the test to verify the result.

    Smoking may also increase GGT concentrations.

    Levels of GGT increase with age in women, but not in men, and are always somewhat higher in men than in women.

    Several drugs increase (induce) the concentration of GGT in the blood. The increases do not indicate damage to the liver. Please inform your doctor of any prescription or non prescription drugs that you are taking.

  • Can my GGT be raised if I don't have any symptoms?

    Yes, GGT is very sensitive and can be increased when you don't have symptoms. This elevation may be temporary, perhaps due to medications you are taking or alcohol ingested within 24 hours of the test. If other liver enzymes are normal, your doctor may just wait and then repeat the GGT test. If the GGT is very high and/or your other liver enzymes are raised, your doctor may want to do more extensive testing to search for the cause.

  • I am an alcoholic but I have stopped drinking. Will my GGT ever go back to normal?

    Over time, your GGT level will fall from whatever level it was at the time when you stopped drinking alcohol to a near normal state. It takes at least a month and sometimes longer for GGT to return to normal after you stop drinking. Abstaining from alcohol will decrease your chances of further damaging your liver and should allow your liver functions to improve.