What is Gamma-Glutamyl Transpeptidase (GGT) Test?
The gamma-glutamyl transpeptidase (GGT) test measures the amount of the enzyme GGT in your blood. Enzymes are molecules that are necessary for chemical reactions in your body. GGT functions in the body as a transport molecule, helping to move other molecules around the body. It plays a significant role in helping the liver metabolize drugs and other toxins.
GGT is concentrated in the liver, but it’s also present in the gallbladder, spleen, pancreas, and kidneys. GGT blood levels are usually high when the liver is damaged. This test is often done with other tests that measure liver enzymes if there’s a possibility of liver damage. Read more about other liver function tests.
Why is Gamma-Glutamyl Transpeptidase (GGT) Test performed?
Your doctor may order the GGT test if they suspect your liver is damaged or if you have a liver disease, particularly if it’s related to alcohol use. The GGT test is currently the most sensitive enzymatic indicator of liver damage and disease. This damage is often caused by heavy use of alcohol or other toxic substances, like drugs or poisons.
If you’ve finished an alcohol rehabilitation program and you’re trying to abstain from alcohol, your doctor might order this test to check that you’re following the treatment program. The test can also monitor GGT levels for people who have been treated for alcoholic hepatitis.
What should I know before receiving Gamma-Glutamyl Transpeptidase (GGT) Test?
Even small amounts of alcohol within 24 hours of a GGT test may cause a temporary increase in the GGT. Smoking can also increase GGT.
Elevated GGT levels may be an indicator of cardiovascular disease and/or hypertension. Some studies have shown that people with increased GGT levels have an elevated risk of dying from heart disease, but the reason for this association is not yet known.
Drugs that may cause an elevated GGT level include phenytoin, carbamazepine, and barbiturates such as phenobarbital. Use of many other prescription and non-prescription drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs), lipid-lowering drugs, antibiotics, histamine receptor blockers (used to treat excess stomach acid production), antifungal agents, antidepressants, and hormones such as testosterone, can increase GGT levels. Clofibrate and oral contraceptives can decrease GGT levels.
Levels of GGT increase with age in women, but not in men, and are always somewhat higher in men than in women.
There’s a chance of slight bleeding at the insertion site or of getting a hematoma — a blood bruise under the skin. Infection only occurs in very rare cases.
How to prepare for Gamma-Glutamyl Transpeptidase (GGT) Test?
Your doctor may instruct you to fast for eight hours before the test and to stop taking certain medications. If you drink even a small amount of alcohol within 24 hours of the test, it can affect your results.
What happens during Gamma-Glutamyl Transpeptidase (GGT) Test?
A regular blood test can measure your GGT level. Usually, blood is drawn from your arm at the crease of your elbow. The healthcare provider will put an elastic band around your arm to make your veins more prominent. Then, they will draw blood through a syringe and collect it in a vial for analysis. You may feel a sting or a prick when the needle is inserted. You might feel throbbing and have a small bruise later.
What happens after Gamma-Glutamyl Transpeptidase (GGT) Test?
This test doesn’t require any special aftercare. You may resume your daily activities unless instruced otherwise by your doctor.
If you have any questions about the Gamma-Glutamyl Transpeptidase (GGT) Test, please consult with your doctor to better understand your instructions.
Explanation of results
What do my results mean?
The normal range for GGT levels is 9–48 units per liter (U/L). Normal values can vary due to age and sex.
An elevated GGT level suggests that a condition or disease is damaging the liver but does not indicate specifically what. In general, the higher the level, the greater the damage to the liver. Elevated levels may be due to liver diseases, such as hepatitis or cirrhosis, but they may also be due to other conditions, such as congestive heart failure, diabetes, or pancreatitis. They may also be caused by alcohol abuse or use of drugs that are toxic to the liver.
A low or normal GGT test result indicates that it is unlikely that a person has liver disease or has consumed any alcohol.
A high GGT level can help rule out bone disease as the cause of an increased ALP level, but if GGT is low or normal, then an increased ALP is more likely due to bone disease.
GGT is sensitive to fluctuations. If your doctor thinks your temporary use of medications or alcohol is affecting the test, they might want you to be tested again. Barbiturates, phenobarbital, and some nonprescription drugs can increase the levels of GGT in your body. Levels of GGT increase with age in women, but not in men.
If you have recently stopped drinking heavily, it can take up to a month for your GGT to fall to normal levels.
Depending on the laboratory and hospital, the normal range for Gamma-Glutamyl Transpeptidase (GGT) Test may vary. Please discuss with your doctor any questions you may have about your test results.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Review Date: November 7, 2018 | Last Modified: September 12, 2019
Gamma-Glutamyl Transpeptidase (GGT) Test. https://www.healthline.com/health/gamma-glutamyl-transpeptidase. Accessed October 25, 2018.
Gamma-Glutamyl Transferase (GGT). https://labtestsonline.org/tests/gamma-glutamyl-transferase-ggt. Accessed October 25, 2018.