A gamma-glutamyl transferase (GGT) test is a blood test providers use to diagnose or rule out liver and bile duct conditions. It measures levels of GGT, an enzyme found mostly in your liver that helps protect your cells from damage. Alcohol, medications and conditions that affect your liver, pancreas or heart can cause high GGT levels.
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Gamma-glutamyl transferase (GGT) is an enzyme (something that helps chemical reactions happen) found mainly in your liver, though it can be found throughout your body. It helps protect your cells from damage — so, high levels of it can mean it’s working hard against damage in your body.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
A gamma-glutamyl transferase (GGT) test is a blood test a healthcare provider orders to check for liver damage or a bile duct blockage. It measures the amount of GGT, a liver enzyme, in your blood.
High levels of GGT can indicate a number of health conditions that affect your liver, your heart or other organs. Alcohol and certain medications can also cause high levels of GGT. Healthcare providers can’t use GGT levels alone to diagnose a disease. They usually order a GGT blood test with other liver function tests to help reach a diagnosis.
Other names for a gamma-glutamyl transferase include:
Healthcare providers most often use GGT blood tests to help diagnose liver disease and/or liver bile duct issues. Your provider may have you get a GGT blood test if you:
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Before a GGT blood test:
Your provider will need to send a sample of your blood to a lab for a GGT test. To get a sample:
The entire procedure usually takes less than five minutes.
After a healthcare provider has collected your blood sample, they’ll send it to a lab for testing. Your healthcare provider will review your results and share them with you, or they’ll appear in your electronic health record.
Blood tests come with a small risk of infection. You may also have a bruise where your provider inserted the needle.
The normal range for GGT is often below 50 U/L (unit per liter), but it can vary based on the lab that performs the test. Always check the reference range provided on your results. It will show a typical, or usual range for the results.
It’s important to note that GGT levels are, on average, somewhat higher in people assigned male at birth (AMAB) than in people assigned female at birth (AFAB). They can also vary with age.
In most cases, you should have your test results within one to two business days, though it could take longer.
Having higher-than-normal GGT levels in your blood may indicate that a condition or disease is damaging your liver. But GGT levels alone can’t identify the specific cause of the damage.
Liver conditions that can cause elevated GGT levels include:
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Other conditions that can cause elevated GGT levels include:
It’s important to know that having a high GGT test result doesn’t necessarily mean you have a medical condition. Other factors can affect your GGT levels. Your healthcare provider will take your other blood test results and your medical history into consideration when analyzing your results.
Talk to your provider if you have any questions about why you need a GGT test or what the results mean.
Seeing a test result that’s not as expected can be stressful. The thing about GGT levels is that they don’t indicate any specific disease on their own, so an internet search may not be able to give you quick answers about what your results mean for you. Your provider will use your other test results, any symptoms you’re experiencing and your health history to come to a diagnosis. They can help you understand what your specific results mean for your health.
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Last reviewed on 10/21/2024.
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