Gamma-glutamyl Transferase (GGT) Test
Reviewed
Also called: gamma-glutamyl transpeptidase, GGTP, Gamma-GT, GTP
A gamma-glutamyl transferase (GGT) test measures the amount of GGT in your blood.
Specimen: blood
Why this test may be ordered
- To help diagnose liver disease.
- To determine if liver damage is due to liver disease or a bone disorder.
- To check for blockages in the bile ducts.
- To screen for or monitor alcohol use disorder (AUD).
Preparation and collection
Talk to your provider to see if there are any specific instructions, since. the results of your GGT test may be affected by: Certain medicines or supplements, Drinking alcohol, Smoking cigarettes. Your provider may also ask you to fast for a certain amount of time before testing.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Your provider will consider your symptoms, medical history, and the results of other blood tests to understand the results of your GGT test.
- Higher than normal GGT: If your results show higher-than-normal levels of GGT, it may be a sign of liver damage. Usually, the higher the level of GGT, the more liver damage you have. Limitation: The results can't tell you which condition is causing your liver damage, but they can help show how much damage there is. Next step: In addition to an ALP test, your provider may order liver function tests with or after the GGT test.
- Low or normal GGT: If your results show low or normal levels of GGT, you probably don't have liver disease. Limitation: High levels of ALP and low or normal GGT levels mean it's more likely you have a bone disorder. Next step: If you have questions about your results, talk to your provider.
- Cannot diagnose the specific cause of liver disease; only indicates liver damage.
- Results may be affected by certain medicines, supplements, alcohol, smoking, or recent meals.
- Provides no information about bone disorders without comparison with an ALP test.
What to do next
If you have questions about your results, talk to your provider. In addition to an ALP test, your provider may order liver function tests with or after the GGT test.
- What do my GGT results mean in combination with my ALP and other liver tests?
- Do I have any signs of liver damage that need further investigation?
- Should I avoid any medications or alcohol before a repeat test?
- How often should I have this test if I am being monitored for alcohol use disorder?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Gamma-glutamyl Transferase (GGT) Test