gamma-glutamyltransferase (GGT) in serum

Physiology

• gamma-Glutamyltransferase plays a major role in glutathione metabolism & in resorption of amino acids from the glomerular filtrate
• also important in the absorption of amino acids from the intestinal lumen.
• GGT is found mainly in the liver, pancreas & kidney
• lower activities can be found in most other organs.

Reference interval

• Male & Female: 3.0 - 59.0 U/L
• < 30 U/L

Principle

The Kodak Ektachem Clinical Chemistry Slide (GGT) is a dry, multilayered analytical element coated on a clear polyester support.

An 11 uL drop of sample is deposited on the slide & evenly distributed by the spreading layer. GGT catalyzes the transfer of the delta-glutamyl moiety of L-gamma-glutamyl-p-nitroanilide to glycylglycine, simultaneously producing p-nitroaniline. The rate change in reflection density is measured & is used to calculate the enzyme activity of GGT.

The reaction sequence involved:

L-gamma-glutamyl-p-nitroanilide   GGT      p-nitroaniline
+ Glycylglycine (Gly-Gly)      ------->  + gamma-glutamyl-GlyGly

Clinical significance

• sensitive indicator of hepatobiliary disease
• useful in diagnosis of
  • obstructive jaundice
  • chronic alcoholic liver disease
• useful in identifying hepatobiliary source of elevated serum alkaline phosphatase
• useful in follow-up of chronic alcoholics undergoing treatment
• detection of hepatotoxicity
• more responsive to biliary obstruction than serum AST, serum ALT or serum alkaline phosphatase

Increases

• hepatobiliary disease & biliary obstruction (largest increases)
  • cholangitis
  • cholecystitis
• liver disease
  • inflammation
  • cirrhosis
  • space-occupying lesions
• infectious mononucleosis
• renal transplant
• hyperthyroidism
• myotonic dystrophy
• diabetes mellitus
• pancreatitis & pancreatic cancer
• alcohol-induced liver disease
• pregnancy
• lipoid nephrosis (mild)
• pharmaceutical agents
  • acetaminophen toxicity
  • barbiturates
  • captopril
  • cephalosporins
  • estrogens (oral contraceptives
  • phenytoin
  • primidone
  • propoxyphene
  • streptokinase

GGT is a useful marker for: (level reflect recurrence)

• pancreatic cancer
• prostate cancer
• hepatoma
• carcinoma metastatic to the liver.

High levels of GGT is found in the urine of patients with urinary tract infection & with destruction of renal tissue.

Risk factor:

• may be risk factor for cardiovascular disease may reflect oxidative stress

Specimen

No special patient preparation required.

Heparin & EDTA may be used as anticoagulants for plasma specimens. No special patient preparation is necessary. Collect the specimen by the standard venipuncture technique.

Remove serum from the clot & analyze as soon as possible.

Sodium fluoride/potassium oxalate should not be used as anticoagulants.

Hemolyzed specimens should not be used.

Ensure equipment is free from soap or glycerol contamination. Collection tubes with glycerol-lubricated stoppers should not be used.

Refrigerate specimen if it cannot be analyzed immediately. Freeze specimen for long-term storage or shipment.

Minimum sample required is 0.5 milliliter with an optimum size of 1.0 milliliter or larger.

More general terms

• gamma-glutamyltransferase in body fluid
• liver (function) tests (LFT, liver panel, hepatic function panel)

Additional terms

• gamma-glutamyltransferase (GGT) or gamma-glutamyltranspeptidase

Component of

• liver (function) tests (LFT, liver panel, hepatic function panel)
• general health panel
• gamma glutamyltransferase/aspartate aminotransferase in serum/plasma

Patient information

gamma-glutamyltransferase (GGT) in serum patient information