Gamma-glutamyl transferase (GGT) is a membrane-bound enzyme found predominantly in hepatocytes and biliary epithelial cells, with lesser expression in the kidneys, pancreas, and intestines. It catalyzes the transfer of gamma-glutamyl groups from glutathione to acceptor molecules, playing a key role in glutathione metabolism and amino acid transport. Serum GGT is widely used as a sensitive marker of hepatobiliary disease and is particularly responsive to alcohol consumption and enzyme-inducing medications. GGT is anchored to the outer surface of cell membranes and is involved in the hydrolysis of extracellular glutathione, contributing to cellular antioxidant defense and amino acid uptake. In the liver, it is highly expressed in the canalicular membranes of hepatocytes and biliary epithelium, making it exquisitely sensitive to cholestatic injury and hepatocellular damage. Serum GGT levels reflect the balance between hepatic synthesis, biliary excretion, and cellular release due to membrane injury or enzyme induction.
Gamma-glutamyl transferase (GGT) is an enzyme found primarily in the liver and bile ducts. It catalyzes the transfer of gamma-glutamyl groups and plays a role in glutathione metabolism. GGT is one of the most sensitive enzymatic indicators of hepatobiliary disease and oxidative stress, often rising before other liver markers.
Elevated GGT is associated with bile duct obstruction, hepatic steatosis (fatty liver), alcohol consumption, and medication-induced hepatotoxicity. It also correlates with oxidative stress and has been identified as an independent predictor of cardiovascular events and metabolic syndrome in epidemiological studies.
Oral supplements metabolized by the liver, NSAID use, and very high protein intake can elevate GGT independent of liver disease. Interpreting GGT alongside ALT and AST helps distinguish hepatic origin from other causes. Isolated GGT elevation without concurrent ALT/AST elevation is less specific for liver injury.
Turnaround Time
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