Preparation: Typically, no fasting is required, but you may be advised to avoid alcohol and certain medications that could affect the liver for 24 hours before the test. 

The Gamma-Glutamyl Transferase (GGT) test measures the level of GGT, an enzyme found in the liver, bile ducts, and pancreas. It is primarily used to assess liver health, diagnose liver disease, and identify bile duct issues. Elevated GGT levels can indicate liver damage, alcohol abuse, or bile duct obstruction.