Gamma-glutamyl transpeptidase (GGT)

A blood test performed to determine the level of gamma-glutamyl transpeptidase.

The measurement of gamma-glutamyltransferase activity is used in the diagnosis and treatment of cholestatic hepatitis. GGTP is an enzyme found in the kidneys and the liver.

What is GGTP?

GGTP (gamma-glutamyl transpeptidase) is an enzyme found in the cells of many organs.

The GGTP test is used mainly in the diagnosis of liver and biliary tract diseases. GGTP measured in blood serum originates primarily from the bile ducts and the liver.

Testing the GGTP level is one of the components of the liver function panel. Usually, for a comprehensive assessment of liver condition, in addition to this test, the levels of aminotransferases and alkaline phosphatase (ALP) should also be determined.

What does the test diagnose?

An increased GGTP level may be a sign of liver dysfunction or developing gallstone disease.

In addition, it may indicate cholestasis, which is the stagnation of bile in the bile ducts. Cholestasis is a serious health-threatening condition, as bile acids cause damage to liver cells and impair digestion.

Abnormal GGTP levels are also found in people with liver cancer, those developing alcohol-related liver disease, or those infected with viral hepatitis. In the suspicion of any of these conditions, a physician may recommend testing GGTP levels.

The GGT test may also be performed to determine the cause of elevated alkaline phosphatase (ALP) levels—whether due to diseases of the bile ducts or liver, or bone disease.

When is it worth performing a GGTP test?

An increase in activity is observed in:

• intrahepatic and extrahepatic cholestasis,
• inflammation of the bile ducts,
• hepatitis,
• alcohol-related disease.

Important information

• The test involves drawing blood from a vein, which is then sent to the laboratory for analysis.
• The blood collection takes approximately several to a dozen seconds.
• No special preparation is required for the test.
• The blood sample should be collected in the morning hours.

GGTP – how to prepare for the blood test?

You should prepare properly for the test. Blood should be collected on an empty stomach. What does this mean? You should refrain from eating and drinking beverages other than water for 8 to 12 hours before the blood draw. This recommendation applies to all blood tests, as food intake may affect the result, and any deviations from normal values or changes in the proportions and levels of the tested parameters are difficult to predict.

The day before the test, you should avoid very fatty, heavy, fried meals and dishes. Consuming even small amounts of alcohol is also not recommended (2–3 days before the test). Smoking may also increase GGT levels.

On the day of the test, you may drink a small amount of water, which will make blood collection easier. Blood should be drawn in the morning; however, in most cases this is not a problem—collection points operate during hours adapted to the requirements of blood sampling. Before the test, rest in a seated position for about 10–15 minutes. It is recommended to arrive at the collection point early to avoid rushing and to ensure comfort while also taking care of the test result.

In patients receiving long-term treatment, the intake of the morning dose of medications on the day of blood collection should be consulted with a physician.

Also inform your physician about any medications or herbal preparations you are taking.

The decision on how to prepare for the test should always be made by the physician.

GGTP reference ranges

GGTP reference ranges depend, among other factors, on the patient’s sex; normal values for women and men differ slightly. Reference values may vary depending on the laboratory.

In the case of abnormal results, consultation with a physician is recommended for a detailed discussion.

• Test results available within 3 business days,
• Possibility to collect the result at the reception of the previously selected Medical Center,

After completing the test at a Medicover Medical Center, you can access your results online.

1. Download the Medicover OnLine app on your phone from Google Play or the App Store.
2. Log in to the app via a secure online banking system or, during your visit to the Collection Point, receive a password for the app at the reception of the Medicover Center.

Factors that may affect the test result

• smoking,
• alcohol,
• use of certain medications.

Who should you consult about abnormal results?

• Gastroenterologist
• Internist 

Watch how to log in to the Medicover OnLine app