Gamma-Glutamyl Transferase (GGT)

An elevated GGT level indicates that something is damaging the liver but does not indicate specifically what. Generally, the higher the GGT level the greater the damage to the liver.  Therefore, a high GGT level typically warrants further testing. Elevated levels may be due to liver diseases (such as hepatitis or cirrhosis), or they may be due to other conditions (such as congestive heart failure, diabetes, or pancreatitis). As mentioned above, alcohol abuse and smoking can also cause elevated GGT, as well as drugs that are toxic to the liver, including: phenytoin, carbamazepine, and barbiturates. In addition, use of many other prescription and non-prescription drugs, including NSAIDs, lipid-lowering drugs, antibiotics, stomach acid reducers, antifungal agents, antidepressants, and testosterone can increase GGT levels.

It is worth noting that GGT levels increase with age in women, but not in men, and are always somewhat higher in men than in women. 

Decreased GGT levels are associated with vitamin B6 and magnesium deficiency.

A low or normal GGT test indicates that liver damage in unlikely or the person hasn’t consumed any alcohol recently.

It is worth noting that use of clofibrate and oral contraceptives can decease GGT levels. 

Gamma-Glutamyl Transferase (GGT) is an enzyme most commonly associated with the liver. GGT tests are often run to determine the cause and extent of liver damage or to monitor treatment of alcohol abuse disorders. While an elevated GGT score may be a cause for concern, a normal or low score is generally not.