Gamma-glutamyl transpeptidase
Alternative Names: Gamma-GT; GGTP; GGT
Gamma-glutamyl transpeptidase (GGT) is a test to measure the amount of the enzyme GGT in the blood.
Why is the Test Performed?
This test is used to detect diseases of the liver or bile ducts. It is also done with other tests (such as the ALT, ALP, and bilirubin tests) to tell the difference between liver or bile duct disorders and bone disease.
How is the Test Performed?
A blood sample is needed. For information on how this is done, see: Venipuncture
Preparation for the Test
The health care provider may advise you to stop taking any drugs that can affect the test.
- Drugs that can increase GGT levels include alcohol, phenytoin, and phenobarbital.
- Drugs that can decrease GGT levels include clofibrate and birth control pills.
How will the Test Feel?
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Gamma-glutamyl transpeptidase Risks
There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Bleeding from where the needle was inserted
- Fainting or feeling light-headed
- Hematoma (blood collecting under the skin)
- Infection (rare)
Normal Results for Gamma-glutamyl transpeptidase
The normal range is 0 to 51 international units per liter (IU/L).
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What Abnormal Results Mean
Greater-than-normal levels of GGT may indicate:
- Alcohol abuse
- Flow from the liver is blocked (cholestasis)
- Heart failure
- Hepatitis
- Liver ischemia (lack of blood flow)
- Liver necrosis
- Liver tumor
- Scarring of the liver (cirrhosis)
- Use of drugs that are toxic to the liver
Learn more about Gamma-glutamyl transpeptidase
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Copyright 2011 A.D.A.M., Inc.
