GGT is a microsomal enzyme which multiply in users of alcohol , barbiturates , phenytoin and some other drugs certain . Alcohol not only stimulate microsomal enzymes to produce more , but also cause liver damage , even though the drink was a good nutritional status . High levels of GGT occur after 12-24 hours for people who drink alcohol in large quantities , and will probably remain elevated for 2-3 weeks after the intake of alcohol is stopped . Gamma – GT test is considered more sensitive than alkaline phosphatase tests ( alkaline phosphatase , ALP ) .