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Lab Test: Gamma-Glutamyl Transferase, GGT Level

    Lab Test
    • Gamma-Glutamyl Transferase (GGT)
    • Measurement of gamma-glutamyltransferase (gamma-glutamytranspeptidase) in serum for the evaluation and management of hepatobiliary dysfunction. 
    • A sensitive indicator of hepatobiliary disease. 
    • Used as an indicator of heavy and chronic alcohol use.
    Reference Range
    • Adults:  1-94 units/L
    • Neonates, cord blood:  11-194 units/L (0.19-3.3 microkatal/L)
    • Neonates, 0 to 1 month:  0-151 units/L (0-2.57 microkatal/L)
    • Infants, 1 to 2 months:  0-114 units/L (0-1.94 microkatal/L)
    • Infants, 2 to 4 months:  0-81 units/L (0-1.38 microkatal/L)
    • Infants, 4 to 7 months:  0-34 units/L (0-0.58 microkatal/L)
    • Children, 7 months to 15 years:  0-25 units/L (0-0.43 microkatal/L)
    Indications & Uses
    • Suspected alcohol use - from 35% to 85 of heavy drinkers have increased GGT levels after episodes of acute drinking; GGT is believed to be the most sensitive indicator of recent heavy drinking.  An elevated GGT appears to have moderate sensitivity and high specificity for identifying active drinkers.
    • Liver cell dysfunction - highly accurate in indicating even the slightest degree of cholestasis
    • Biliary obstruction
    • Cholangitis
    • Cholecystitis
    • Chronic alcohol ingestion - GGTP is elevated in approximately 75% of patients who chronically drink alcohol
    • Acute myocardial infarction (AMI) - why GGTP is elevated is not clear.  Elevation usually occurs 1 to 2 weeks after infarction
    Clinical Application
    • The enzyme GGTP participates in the transfer of amino acids and peptides across the cellular membrane and possibly participates in glutathione metabolism. The highest concentrations of this enzyme are found in the liver and biliary tract.  Smaller amounts are found in the kidney, spleen, heart, intestine, brain, and prostate gland. 
    • Men may have higher GGTP levels than women because of the additional levels in the prostate.  The elevation of GGTP generally parallels that of alkaline phosphatase; however, GGTP is more sensitive.  It is not increased in bone diseases, as is alkaline phosphatase.  A normal GGTP level with an elevated alkaline phosphatase level would imply skeletal disease.  An elevated GGTP and elevated alkaline phosphatase level would imply hepatobiliary disease. 
    • Increased levels may indicate:
      • Liver diseases, (e.g., hepatitis, cirrhosis, hepatic necrosis, hepatic tumor or metastasis, hepatotoxic drugs, cholestasis, or jaundice), myocardial infarction (MI), alcohol ingestion, pancreatic diseases (e.g., pancreatitis, cancer of the pancreas), or Epstein-Barr virus (EBV) (infectious mononucleosis, cytomegalovirus infections, Reye syndrome, renal transplant, hyperthyroidism, myotonic dystrophy, diabetes mellitus, African ancestry obesity, moderate to heavy smoking, acute renal failure, stroke.
    • Results decreased in: 
      • Females, hypothyroidism, or pregnancy.
    Related Tests
    • Alanine aminotransferase (ALT) - this liver enzyme is elevated in hepatocellular disease.
    • Alkaline phosphatase (ALP) - this test is used to detect and monitor diseases of the liver or bone. 
    • Aspartate aminotransferase (AST) - this liver enzyme is elevated in hepatocellular disease.
    • 5'-nucleotidase - this liver enzyme is elevated in diseases affecting the biliary tree.
    • Creatine phosphokinase (CPK) - this enzyme is similar to AST and exists predominantly in the heart and the skeletal muscle.
    • Lactic dehydrogenase (LDH) - this intracellular enzyme is used to support the diagnosis of injury or disease involving the heart, liver, red blood cells, kidneys, skeletal muscle, brain, and lungs. 
    • Leucine aminopeptidase (LAP) - this enzyme is specific to the hepatobiliary system.  Diseases affecting that system will cause elevation of this enzyme. 
    • General healthy panel
    • Hepatic function panel
    Drug-Lab Interactions
    • Values may be decreased in late pregnancy.
    • Drugs that may cause increased levels include:  alcohol, phenobarbital and phenytoin (Dilantin). 
    • Drugs that may cause decreased levels include:  clofibrate and oral contraceptives.
    Test Tube Needed
    • Red top tube
    • Collect a venous blood sample.
    • Apply pressure or a pressure dressing to the venipuncture site and assess the site for bleeding. 
    • Patients with liver dysfunction often have prolonged clotting times.
    Storage and Handling
    • May store specimen for 1 months at 4°C or 1 year at -20°C.
    What To Tell Patient Before & After
    • Explain the procedure to the patient.
    • Tell the patient that an 8-hour fast is recommended.  Only water is permitted.
    • Pagana K, Pagana TJ eds. Mosby's Manual of Diagnostic and Laboratory Tests. 5th Ed.  St. Louis, Missouri. 2014.

MESH Terms & Keywords

  • Gamma-Glutamyl Transferase, GCT Level