Gamma Glutamyl Transferase (GGT)

Key Aspects of GGT:

• Purpose: GGT helps transport amino acids and metabolizes glutathione, acting as a key marker for liver injury, particularly cholestasis (bile flow stoppage).
• What High Levels Mean: While commonly associated with alcohol abuse, elevated GGT can indicate fatty liver, hepatitis, cirrhosis, bile duct tumours, pancreatitis, or drug toxicity.
• When It’s Tested: Often ordered alongside other tests (like ALT, ALP, AST) to investigate liver issues, especially if the patient has jaundice, dark urine, or abdominal pain.
• Normal Range: Typical levels range from 5 to 40 units per liter (U/L), though this can vary by lab and is often higher in newborns or with age in females.
• Sensitivity: GGT is highly sensitive to liver injury, but not very specific—meaning it can show as high for many different causes, including diabetes or heart failure.

Causes of Elevated GGT Levels:

• Alcohol Use: Regular, heavy alcohol consumption often significantly raises GGT.
• Liver Disease: Fatty liver, hepatitis, or cirrhosis.
• Bile Duct Blockage: Conditions that block bile flow from the liver.
• Medications: Certain over-the-counter and prescription drugs, including phenytoin and phenobarbital.
• Other Factors: Smoking, heart failure, diabetes, and certain infections.

What to Expect (Test Procedure):

• Preparation: Usually requires fasting, as food can cause a temporary decrease in GGT levels.
• Procedure: A standard blood draw (venipuncture).
• Risks: Generally, there are very few risks, such as minor bruising or pain at the site.