The GGT test helps to detect liver and bile duct injury. GGT can also be used to screen for chronic alcohol abuse (it is likely to be high in 75% of chronic drinkers). Elevated levels may be due to liver disease, but they may also be due to congestive heart failure, alcohol, prescription drugs, anti fungal agents, and hormone such as testosterone. Even a small amount of alcohol within 24 hours of your GGT test may cause a temporary increase in GGT. Smoking can also increase GGT.