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Liver Function Tests

Gamma Glutamyl Transferase



  • Gamma glutamyl transferase (GGT) is an enzyme found in hepatocytes and biliary epithelial cells, and is a sensitive yet non-specific marker of hepatocyte damage.
      • Normal Range

      • Males: <50 U/L
      • Females: <30 U/L
  • GGT is used as a marker of cholestasis, though may also be raised in the setting of certain other conditions, especially due to alcohol intake.
  • ALP and GGT may also be mildly elevated in the presence of hepatocellular disease, with predominant derangement of the transaminases.

Cholestatic LFT Derangement

    • Look For

    • Elevated ALP and GGT
    • Mildly elevated ALT / AST
    • Elevated conjugated bilirubin
    • Causes of Cholestasis

    • Intrahepatic Cholestasis

    • Hepatitis (viral or alcoholic)
    • Autoimmune liver disease - primary biliary cirrhosis, primary sclerosing cholangitis
    • Infiltrative liver disease - amyloidosis, sarcoidosis, tuberculosis, lymphoma
    • Malignancy - hepatocellular carcinoma, cholangiocarcinoma, metastasis
    • Non-malignant mass - abscess, cystic liver disease, haematoma
    • Sepsis
    • Acalculous cholecystitis
    • Intrahepatic cholestasis of pregnancy
    • Total parenteral nutrition
    • Drugs - augmentin, isoniazid, rifampicin, chlorpromazine
    • Extrahepatic Cholestasis

    • Choledocholithiasis
    • Bile duct stricture
    • Parasitic infection of bile duct
    • Primary sclerosing cholangitis
    • Pancreatitis
    • Pancreatic cyst
    • Malignancy - pancreas, ampulla, common bile duct, gallbladder

Isolated GGT Elevation

  • Isolated elevation of GGT is generally suggestive of a non-hepatobiliary cause, and is classically a sign of alcohol intake.
    • Causes of Isolated GGT Elevation

    • Significant alcohol intake (usually >2 drinks per day)
    • Pancreatitis
    • COPD
    • Renal failure
    • Diabetes
    • Myocardial infarction
    • Drugs - phenytoin, carbamazepine, paracetamol, tricyclic antidepressants
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