The Gamma Glutamyl Transferase (GGT) test is a blood test that measures the level of the GGT enzyme in the blood. The GGT enzyme is produced in the liver and is involved in the metabolism of drugs and toxins. The GGT test is commonly used to detect liver damage, including liver disease or alcohol abuse. Elevated levels of GGT can also indicate other conditions, such as biliary obstruction or pancreatic disease. The test is often done in conjunction with other liver function tests, such as the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) tests, to help diagnose liver disease. The GGT test is a simple and relatively non-invasive procedure that involves drawing a blood sample from a vein. Abnormal levels of GGT may require further testing or evaluation by a healthcare provider.