Abstaining from alcohol or stopping the medications that resulted in the increased GGT levels lowers the GGT level, according to Lab Tests Online. Doctors use the GGT test to detect liver disease and bile duct obstruction.
Small amounts of alcohol consumed within 24 hours of testing may cause an increase in GGT levels, according to Lab Tests Online. GGT can also screen for chronic alcohol abuse as GGT levels are raised in the majority of chronic alcohol drinkers.
Besides being elevated in liver and bile duct diseases and in alcohol drinkers, smoking also elevates GGT, notes Lab Tests Online. Some medications, such as phenytoin, carbamazepine, non-steroidal anti-inflammatory drugs, lipid-lowering drugs, antibiotics, antifungal agents and antidepressants, can also increase GGT levels.
Doctors often order GGT together with other tests of liver function, such as ALP, AST and ALT. If the levels of all these liver markers are not elevated and there is an isolated elevation of GGT, it may be due to alcohol consumption. If the GGT levels were transiently increased due to alcohol taken 24 hours before the blood test, the levels fall to normal if the blood test is repeated. If elevated GGT levels were due to chronic alcohol consumption, it can take several weeks to a month for the levels to fall after abstaining from alcohol, according to Lab Tests Online.