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.
- 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
- Elevated ALP and GGT
- Mildly elevated ALT / AST
- Elevated conjugated bilirubin
Causes of 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
- Acalculous cholecystitis
- Intrahepatic cholestasis of pregnancy
- Total parenteral nutrition
- Drugs - augmentin, isoniazid, rifampicin, chlorpromazine
- Bile duct stricture
- Parasitic infection of bile duct
- Primary sclerosing cholangitis
- 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)
- Renal failure
- Myocardial infarction
- Drugs - phenytoin, carbamazepine, paracetamol, tricyclic antidepressants