GGT is an enzyme mainly found in mainly in liver cells (but is also found in cells of the kidney and pancreas) and plays a key role in the detoxification of drugs and alcohol by the liver.
GGT is measured as part of a routine liver profile test along with AST (aspartate aminotransferase), ALP (alkaline phosphatase), ALT (alanine aminotransferase) and bilirubin if the there are symptoms suggesting a liver disorder. Some of the symptoms of liver injury include jaundice, nausea, vomiting, abdominal swelling, abdominal pain, pruritus (severe itching), and tiredness. The measurement of GGT is also useful when ALP is raised to determine if the source of the ALP is the liver or the bone.
GGT can be used with other markers to predict the presence of non-alcoholic fatty liver disease. This is a condition where fat is stored in the liver due to an unhealthy diet and lifestyle. This can eventually lead to cirrhosis of the liver if left unchecked and affects 1 in 3 people in the UK. It also useful as an indicator of liver damage due to excessive alcohol intake. GGT levels may also be used to monitor alcohol consumption in patients with chronic alcoholism, GGT levels usually take as long as 1 month to normalize after cessation of alcohol consumption.
GGT levels can be increased in patients with liver diseases in general, including acute and chronic hepatitis, cirrhosis, alcoholic liver disease and blocked bile ducts (cholestasis). GGT can also be increased when you don't have symptoms due to medications including some antibiotics and antidepressants or alcohol consumed within 24 hours of the test. If other liver enzymes are normal it is recommended to wait and repeat the GGT test.