Gamma-glutamyl transpeptidase (GGT) is an enzyme made in the liver. Some is released into the blood stream. Higher than normal blood levels of GGT may indicate recent alcohol use or a liver problem. Also, many medications can cause a high GGT on a blood test.

Even though you don't take any prescription drugs, you might be taking an over-the-counter drug, herb, or supplement that is causing the elevated GGT. Examples include:

• Acetaminophen (Tylenol and generic versions, alone or part of combination pain relief and cold remedies)
• Ibuprofen (Advil, Motrin, generics)
• Naproxen (Aleve, generics)
• Vitamin A in high doses

Many herbal products have been reported to cause an abnormal GGT. Kava and black cohosh have been associated with severe liver damage.

Two relatively common liver conditions that could cause an elevated GGT are fatty liver (non-alcoholic steatohepatitis) and hepatitis C infection. Very often there are no symptoms with these conditions.

Life and health insurance companies often run a GGT test on blood taken as part of a qualifying exam.

Talk to your doctor. Your doctor will likely order additional blood tests that will give you a better picture of whether there is an underlying liver problem.