An elevated level of gamma-glutamyl transpeptidase, or gamma GT, is defined as any level above 51 international units per liter. Normal range for gamma GT is anywhere between 0 and 51 international units per liter.
Gamma GT is an enzyme that is tested to detect diseases of the liver or bile duct. The test for the Gamma GT enzyme is known as a gamma-glutamyl transferase blood test. This blood test can also be used to determine the cause for an elevated level of alkaline phosphatase in the blood. Patients with elevated phosphatase in their blood may have a bone disease, liver disease or bile duct disease. However, patients with elevated alkaline phosphatase levels in addition to elevated gamma GT levels have either a liver disease or a bile duct disease. In general, elevated levels of gamma GT in the blood point to a problem with the liver or bile duct, though elevated levels do not indicate a specific disease, rather they serve to indicate that an issue exists. This test is ordered when patients are experiencing weakness, nausea, jaundice, dark urine and itching. It may also be ordered for patients with a history of alcohol abuse. Diseases that could cause elevated gamma GT levels include alcoholism, diabetes, hepatitis, liver ischemia, liver necrosis, liver tumor or scarring of the liver.