An elevated gamma-glutamyltransferase, or GGT, is an above-normal level of an enzyme found in the kidney, liver and pancreas, according to Mayo Clinic. Elevated levels are an indication of liver disease.
An elevated GGT is also useful for detecting gall bladder disease, especially if they cause an obstruction in the gall bladder ducts, explains Mayo Clinic. In that case, the GGT levels can be from 5 to 30 times higher than normal. Mildly elevated GGT is a sign of hepatitis, though the test is not as sensitive as other tests for this condition. An elevated GGT can also be an indication of liver tumors. The tumors can have their origins in the liver itself or can have metastasized from another site in the body.
Another use of the GGT test is to discover liver disease caused by alcohol abuse, Mayo Clinic reports. GGT is elevated not only when the liver is severely damaged by alcohol, as with cirrhosis, but it's also higher if the individuals is only a heavy drinker. Certain drugs such as phenytoin can also raise GGT levels. People who have their GGT tested should make sure that these drugs are cleared from their systems first so as not to give a false reading.