Sheryl,

Thanks for your question. 

GGT is a blood test that measures the enzyme gamma-glutamyl transpeptidase in the blood stream, which is produced in the liver, bile ducts and kidneys.  When elevated, it is a sensitive indicator of a problem in the liver and/or bile ducts.  Substances toxic to the liver, like certain drugs and alcohol, can raise the level of this enzyme.  It is often done as part of chemistry screening blood work along with other liver, kidney function, and electrolytes studies. 

It is often used to distinguish between bone problems and liver/bile duct disease.  A more routine test, alkaline phosphatase can be elevated in liver and bone disease.  If the GGT is normal, then the problem is in the bones.  If the GGT is also elevated, then the problem is the liver.

The GGT is not a standard test for high blood pressure.  Your doctor was probably performing routine blood work for screening purposes.

I hope this has been helpful.

Martin Cane, M.D.