What Is a GGT Test?

Written by Jodi Helmer, Markham Heid
Medically Reviewed by Melinda Ratini, MS, DO on February 11, 2025
5 min read

A gamma-glutamyl transferase (GGT) blood test measures the level of the GGT enzyme in your blood. GGT is a common enzyme found in the tissues of the liver and other organs, including the kidneys, pancreas, brain, and heart. It also turns up in your blood and other bodily fluids.

Health conditions like inflammatory bowel disease, stomach cancer, or liver disease can cause many of the same symptoms – stomach pain, fatigue, and a lack of appetite. If you have these, your doctor probably will recommend a few tests to figure out what's going on, and that might include a GGT test.

Experts don't really understand the role GGT plays, but it seems to have something to do with breaking down, changing, and moving proteins and other molecules in your body.

A GGT blood test is usually ordered along with other blood tests to check for diseases or damage to the liver, according to Adam Cloe MD, PhD, a staff pathologist at Quest Diagnostics and spokesperson for the College of American Pathologists.

“A doctor might order a GGT test as part of a panel of tests that are used to check the health of the liver,” he says. “It can also be used to evaluate people if there is concern about alcohol use disorders or other problems that can impact the liver.”

Other tests your doctor may order include: 

  • Alanine transaminase (ALT) test
  • Aspartate aminotransferase (AST)
  • Alkaline phosphatase (ALP)
  • Bilirubin tests
     

Getting your blood drawn for a GGT blood test is as simple as rolling up your sleeve. But your doctor may suggest some extra steps to help you get ready and make sure you get the most accurate results.

“It’s important for patients to talk to their doctors about all medications – including over-the-counter medications and supplements – that they are taking because they may affect the result,” Cloe says. 

Your doctor might ask you to stop taking certain medications that could affect GGT levels. Cloe says that ibuprofen and other nonsteroidal anti-inflammatory (NSAID) medications, antidepressants, antibiotics, and medications used to prevent blood clots can affect GGT levels. Seizure medications – including carbamazepine, phenobarbital, and phenytoin – could increase GGT levels, while birth control pills and clofibrate can cause decreased GGT levels. But do not stop taking any medications unless your doctor tells you to.

Even small amounts of alcohol can increase GGT levels. It’s important not to drink alcohol for at least 24 hours before the GGT test, Cloe says.

How much does a GGT test cost?

GGT blood tests can cost between $9 and $59; the national average for a GGT test is $31.
 

It’s a quick blood test that should take five minutes or so.

  1. You’ll be asked to sit in a chair and roll up your sleeve so the person taking your blood can check your arms – especially the area on the inside of your elbow – for veins they can get to.
  2. The area will be cleaned and disinfected.
  3. A small needle will be inserted to take the blood sample, which is collected in a test tube.
  4. Once the needle is removed, a cotton ball covered with a bandage will be placed over the area to stop the bleeding.

Your doctor will send the blood sample to a lab to be tested for GGT levels. Your provider will call you with the results of your GGT blood work or post them to your electronic health record.

GGT blood test risks

A blood draw is a safe procedure that carries little risk. For some people, getting a blood sample is more challenging because of the size of their veins and arteries, and it might take multiple punctures to locate veins. 

Other possible risks can include:

  • Feeling lightheaded or fainting
  • Infection
  • Excessive bleeding
  • Bruising
  • Blood under the skin (hematoma) 
     

Your results will be in international units per liter, or IU/L. 

The normal range for a GGT result depends on several things, including sex and age as well as the lab that performs it. For an adult male, a typical range of normal results might be 0-65 IU/L and, for an adult female, 0-60 IU/L.

A number of things could cause elevated GGT levels or results that are above the normal range, including:

  • Alcohol use
  • Scarring of the liver (cirrhosis)
  • Swollen or inflamed liver (hepatitis) 
  • Diabetes
  • Heart failure
  • Blockage that prevents the flow of bile from the liver (cholestasis)
  • Lack of blood flow to the liver (liver ischemia)
  • Liver cancer or tumor
  • Lung disease 
  • Pancreatic disease 

But high GGT levels alone aren’t enough for your doctor to know if you have liver disease. For example, doctors often also recommend other tests, including one related to alkaline phosphatase (ALP), another enzyme that can build up in your blood if your liver isn’t working well.

A GGT test can also help doctors diagnose or manage several other medical issues:

 

GGT is a common enzyme found in the liver and other organs. A GGT test is often part of a panel of tests that can also include alanine transaminase (ALT) and aspartate aminotransferase (AST) tests. Elevated GGT levels could be a sign of liver disease or damage.
 

Can GGT return to normal on its own?

GGT levels tend to go back to normal upon treatment or after liver injuries are managed, says Allison Chambliss, PhD, an associate clinical professor of pathology and laboratory medicine at the University of California at Los Angeles. 

“Sometimes, specific treatment may be required,” she says. “In other cases, mildly elevated GGT levels may not require treatment.” 

Which foods should I avoid if my GGT levels are high?

Chambliss advises patients to follow a healthy diet to promote good liver health, adding that those with high GGT should consider limiting or avoiding alcohol, which raises GGT levels.

Is GGT related to cholesterol?

Some studies have found a link between high blood lipid levels and elevated GGT.

“Both GGT and cholesterols may be elevated in patients who have metabolic syndrome,” Chambliss says.

Does high GGT cause weight gain?

Although some studies have found a link between GGT and obesity, Chambliss says it’s unclear if GGT causes weight gain or there are other things at play.