Gamma-Glutamyl Transferase (GGT)

Alternative Names: Gamma Glutamyl Transpeptidase, GGT, Gamma-GT, GGTP, Serum GGT test, Serum GGTP test

The gamma-glutamyl transpeptidase, also known as a GGT blood test, measures the level of the protein (enzyme) GGT in your blood. GGT is concentrated mainly in the liver, but it’s also present in the gallbladder, pancreas, spleen, and kidneys. It is involved with several metabolic processes and increased levels are usually found when liver disease is present.

Interpret now "Complete Blood Count (CBC)"
Interpret now "Urinalysis (UA)"

The GGT blood test is usually done when a doctor suspects that a patient has problems with the bile ducts and liver disease. GGT is a more sensitive indicator of liver pathology than ALT and AST in detecting obstructive jaundice, cholangitis and cholecystitis. In cases of such diseases increased levels of GGT can be found earlier and last longer compared with ALT and AST. The GGT test is also used to check for alcohol problems and to predict the presence of non-alcoholic fatty liver disease (excess fat in liver cells due to an unhealthy diet and lifestyle.).

Gamma-glutamyl transferase (GGT) test can be done to determine the cause of an elevated alkaline phosphatase (ALP). Both ALP and GGT levels rise in case of diseases which affect the bile ducts and in certain liver diseases, but only ALP levels will be elevated when the patient has bone disease. When GGT is normal and the ALP levels are elevated, the cause is probably bone disease.

Normal Levels of GGT

The normal range for GGT levels is approximately 9-48 international units per liter (U/L). Normal value ranges may vary among different laboratories. Also the normal values for liver function tests can vary due to age and sex, at different times of the day and as you get older.

Elevated Levels of GGT

The GGT levels may be very high, e.g. 50 times greater than the upper reference value or just slightly elevated - not more than two times greater than the upper limit of normal. The elevation level should be taken into account. Generally, the higher the GGT level the greater the damage to the liver.

GGT test can't determine the cause of the liver damage, just the fact that it is damaged. To get a more accurate diagnosis it is necessary to pass additional biochemical blood tests – ALT, AST, alkaline phosphatase (ALP), lipase, and others.

Certain medications may influence the result of the GGT test.

Comprehensive Metabolic Panel (CMP) Interpretation