What is a gamma-glutamyl transferase (GGT) test?
A gamma-glutamyl transferase (GGT) test measures the amount of GGT in the blood. GGT is an enzyme found throughout the body, but it is mostly found in the liver. When the liver is damaged, GGT may leak into the bloodstream. High levels of GGT in the blood may be a sign of liver disease or damage to the bile ducts. Bile ducts are tubes that carry bile in and out of the liver. Bile is a fluid made by the liver. It is important for digestion.
A GGT test can't diagnose the specific cause of liver disease. So it is usually done along with or after other liver function tests, most often an alkaline phosphatase (ALP) test. ALP is another type of liver enzyme. It's often used to help diagnose bone disorders as well as liver disease.
gamma-glutamyl transpeptidase, GGTP, Gamma-GT, GTP
What is it used for?
A GGT test is most often used to:
- Help diagnose liver disease
- Figure out if liver damage is due to liver disease or a bone disorder
- Check for blockages in the bile ducts
- Screen for or monitor alcohol use disorder
Why do I need a GGT test?
You may need a GGT test if you have symptoms of liver disease. Symptoms include:
- Jaundice, a condition that causes your skin and eyes to turn yellow
- Loss of appetite
- Abdominal pain or swelling
- Nausea and vomiting
You may also need this test if you had abnormal results on an ALP test and/or other liver function tests.
What happens during a GGT test?
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don't need any special preparations for a GGT test.
Are there any risks to a GGT test?
There is very little risk to having a blood test. You may have slight pain or bruise at the spot where the needle was put in, but most symptoms go away quickly.