Blood test shows gama GT is high at 150. What does it mean?

May just be you. Some people run a GGT that's several times normal, through their lives. Occasionally I have to write letters on behalf of these people, who are accused of being secret alcohol abusers. If the high GGT is brand-new, there may be another explanation. Your physician knows how to follow up.
Abnormal liver test. A GGT is one of several blood tests done to evaluate the function of the liver. A GGT may be elevated in the presence of too much alcohol consumption, hepatitis, other viral illness, chronic overuse of the pain reliever aceteminophen, etc. A doctor might order a repeat of this test and if it continues to be elevated, do further testing to sort out the cause. No alcohol or tylenol (acetaminophen) for now, though!