Quick Guide: Gamma-glutamyl transpeptidase (GGT or GGTP) Blood Test
What it is: A GGT (gamma-glutamyl transferase) test measures the level of GGT, an enzyme found mainly in the liver, in the blood.
Why it's ordered: Ordered to help diagnose liver or bile duct disease, determine whether an elevated ALP is coming from the liver or bone, or screen for alcohol-related liver effects.
What it detects: GGT is a sensitive early marker of liver cell or bile duct injury, though it lacks specificity — it can also rise with alcohol use, certain medications, and non-liver conditions like metabolic syndrome.
Collection & prep: A standard blood draw from a vein in the arm, usually alongside other liver function tests. No special preparation is typically required.
Results:
High – suggests liver or bile duct injury; can also reflect alcohol use or certain medications
Normal – roughly 5–40 U/L, varying by lab and sex
Possible complications of liver injury: An elevated GGT alone doesn't diagnose a specific condition; it's interpreted alongside ALP, ALT, AST, and clinical history to help pinpoint whether the cause is hepatobiliary disease, alcohol use, or something else.
Statements made in the Clinical Manual have not been evaluated by the FDA. The products mentioned are not intended to diagnose, treat, cure or prevent any disease.
