Gamma-glutamyl transpeptidase

Synonyms or Keywords: GGT or GGTP, or Gamma-GT

Overview
Gamma-glutamyl transferase (GGT or GGTP, or Gamma-GT) is primarily a liver enzyme.

Function
It is involved in the transfer of amino acids across the cellular membrane. It is also involved in glutathione metabolism by transferring the glutamyl moiety to a variety of acceptor molecules including water, certain L-amino acids and peptides. Leaving the cysteine product to preserve intracellular homeostasis of oxidative stress.

Location
GGT is found on the cell surface on all cells, with particularly high concentrations in the liver, bile ducts, and kidney.

The enzyme is also present in other tissues, such as the epididymis.

Clinical significance
Its level in the blood may be tested for, as an elevated level may indicate an abnormality in the liver, though this can be caused by a number of conditions including:


 * congestive heart failure
 * cholestasis (congestion of the bile ducts)
 * cirrhosis of the liver
 * Restricted blood flow to the liver
 * restricted venous outflow from liver like Budd-Chiari syndrome
 * Necrosis of the liver
 * Liver tumors
 * hepatitis
 * hepatotoxic drugs

Its levels are increased in chronic and acute alcohol abuse.

Differential Diagnosis
In alphabetical order.

Increased

 * Alcohol
 * Brain tumor
 * Cholestasis
 * Chronic inflammatory bowel disease
 * Cirrhosis
 * Congestive heart failure, particularly right sided heart failure, or "shock liver"
 * Cytomegalovirus infections
 * Diabetes Mellitus
 * Disorders of the lipid metabolism
 * Fatty liver
 * Hepatic necrosis
 * Hepatitis
 * Hepatocellular carcinoma
 * Hepatotoxic drugs
 * Hyperthyroidism
 * Infectious mononucleosis (Epstein-Barr Virus)
 * Inflammation
 * Jaundice
 * Myocardial Infarction
 * Nephritis
 * Obesity
 * Pancreatic cancer
 * Pancreatitis
 * Pneumonia
 * Porphyria
 * Portal vein thrombosis
 * Prostate cancer
 * Restricted blood flow to the liver
 * Restricted venous outflow from liver like Budd-Chiari syndrome
 * Right ventricular failure causing hepatic congestion, also known as "shock liver"

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