Aszpartáttranszamináz

Aszpartáttranszamináz, often abbreviated as AST, is an enzyme found in various tissues throughout the body, including the liver, heart, muscles, kidneys, and brain. Its primary function is to catalyze the transfer of an amino group from aspartate to alpha-ketoglutarate, forming oxaloacetate and glutamate. This reaction is a crucial step in amino acid metabolism and the urea cycle.

In clinical medicine, AST is primarily known as a biomarker for liver damage. When liver cells are injured, AST is released into the bloodstream, leading to elevated levels in blood tests. Similarly, damage to other AST-containing tissues, such as heart muscle damage during a myocardial infarction, can also cause AST levels to rise. However, AST is less specific to the heart than other cardiac enzymes. Muscle injuries, strenuous exercise, and certain medications can also temporarily increase AST levels.

Measurement of AST levels in serum is a common component of liver function tests and is used in the diagnosis and monitoring of various liver conditions, including hepatitis, cirrhosis, and drug-induced liver injury. The ratio of AST to another liver enzyme, alanine transaminase (ALT), known as the AST/ALT ratio, can provide additional information for diagnosing the cause of liver disease. Elevated AST levels, especially when significantly higher than ALT, can sometimes indicate alcoholic liver disease or cirrhosis.