Gamma-Glutamyl Transpeptidase (GGT) Test
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.
Why Is the GGT Test Done?
Your liver is crucial for producing proteins in your body and
filtering out poisons. It also makes bile, a substance that helps your body
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.
The symptoms of liver problems include:
- decreased appetite
- vomiting or nausea
- lack of energy
- abdominal pain
- jaundice, which is a yellowing of the skin
- unusually dark urine
- light-colored feces
- itchy skin
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.
How to Prepare for the 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.
How the GGT Test Is Given
A regular blood test can measure your GGT level. Usually, blood
is drawn from inside the 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 Do the Results Mean?
Your results from the GGT test should be available the following
day. Your doctor will help you interpret them and assess if they’re in the
normal range or not.
The GGT test can diagnose liver damage, but it can’t determine
the cause. If your GGT level is elevated, you’ll probably have to undergo more
tests. Generally, the higher the GGT level the greater the damage to the liver.
Some of the conditions that result in increased GGT include:
- overuse of alcohol
- chronic viral hepatitis
- lack of blood flow to the liver
- liver tumor
- cirrhosis, or scarred liver
- overuse of certain drugs or other toxins
- heart failure
GGT is often measured relative to another enzyme, alkaline
phosphatase (ALP). If GGT and ALP are both elevated, doctors will suspect that
you have problems with your liver or the bile ducts. If GGT is normal and ALP
is elevated, this could indicate bone disease. Your doctor may use the GGT test
in this way to rule out certain problems.
Is the GGT Test Always Accurate?
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 non-prescription
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 more
than a month for your GGT to fall to normal levels. Smoking can also increase
your GGT level.
Risks of GGT Tests
Getting your blood drawn is a relatively low-risk procedure.
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
Liver damage is serious and can often lead to other health
problems. Depending on the extent of the damage, it can also be irreversible. The
GGT test, used in conjunction with other testing methods, can help your doctor see
if you have liver damage.
Be sure to consult your doctor if you have any symptoms related
to liver damage so they can test you and get you started on a treatment