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Liver Function Tests
Liver Function Tests

Gamma Glutamyl Transferase

February 15th, 2021


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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