Gamma-Glutamyl Transferase (GGT) is usually the first liver enzyme to rise in the blood when any of the bile ducts that carry bile from the liver to the intestines become obstructed, for example, by tumors or stones. This makes it the most sensitive liver enzyme test for detecting bile duct problems.
How is the GGT test used?
The gamma-glutamyl transferase (GGT) test may be used to determine the cause of elevated alkaline phosphatase (ALP). Both ALP and GGT are elevated in disease of the bile ducts and in some liver diseases, but only ALP will be elevated in bone disease. Therefore, if the GGT level is normal in a person with a high ALP, the cause of the elevated ALP is most likely bone disease.
The GGT test is sometimes used to help detect liver disease and bile duct obstructions. It is usually ordered in conjunction with or as follow up to other liver tests such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), ALP, and bilirubin. (Read also about the Liver Panel.) In general, an increased GGT level indicates that the liver is being damaged but does not specifically point to a condition that may be causing the injury.
GGT can be used to screen for chronic alcohol abuse (it will be elevated in about 75% of chronic drinkers) and to monitor for alcohol use and/or abuse in people who are receiving treatment for alcoholism or alcoholic hepatitis.
Interestingly, when looked at with low HDL it can be a signal for non-alcoholic fatty liver disease.
What does the GGT test result mean?
An elevated GGT level suggests that a condition or disease is damaging the liver but does not indicate specifically the cause of the damage. 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, metabolic syndrome, diabetes, or pancreatitis. They may also be caused by alcohol abuse, alcoholic liver disease, or use of drugs that are toxic to the liver.
A low or normal GGT test result indicates that it is unlikely that you have liver disease or have consumed any alcohol.
If you are a drinker, there is good news. Over time, your GGT level will fall from whatever level it was at when you stopped drinking alcohol to within the normal range. This can take several weeks to more than a month. Abstaining from alcohol will decrease your chances of further damaging your liver and should allow your liver function to improve.
Summary of GGT
What is gamma-glutamyl transpeptidase?
Gamma-glutamyl transpeptidase (GGT) is an enzyme found mainly in your liver. A GGT test is used to check for signs of liver damage or disease.
What is its function?
GGT plays a key role in breaking down drugs and toxins.
What can cause it to change?
High levels can be a sign of liver damage or disease.
Excessive alcohol consumption will most likely cause your GGT levels to increase. Some drugs, including antibiotics and NSAIDs like ibuprofen, can also increase your levels.
What are the most common symptoms?
If your GGT levels are high as a result of liver damage, common symptoms include:
jaundice — yellow skin and eyes
nausea and vomiting
unexplained weight loss
swelling around your eyes, stomach, or legs
What can I do to change them?
What can you do about it right now?
To prevent high levels caused by liver damage, avoid too much:
Saturated and trans fats — like fried foods, red meat, cakes, pastries, and cream
refined carbohydrates — like white bread and white pasta
added sugars — like fruit juices, fizzy drinks, and sweets
salt — like frozen foods, salted nuts, and smoked or cured meats
alcohol — limit to 14 units a week (equivalent to about 6 pints or 7 medium-sized glasses of wine)