AST is one of the enzymes secreted in liver cells. It is a member of the aminotransferases group. The other member is alanine aminotransferase (ALT) enzyme. The normal value of AST is 0-50 U/L. Aspartate aminotransferase (AST) is one of the tests followed in liver diseases.

AST is one of the enzymes secreted in liver cells. It is a member of the aminotransferases group. The other member is alanine aminotransferase (ALT) enzyme. The normal value of AST is 0-50 U/L. Aspartate aminotransferase (AST) is one of the tests followed in liver diseases. It is especially used in the diagnosis and follow-up of diseases that develop due to damage to liver tissue and cells. AST is especially used in the follow-up and staging of cardiac, hepatic and muscle injuries. Its level also increases in acute myocardial infarction, pulmonary embolism and heart failure. The highest AST level is seen in liver damage.

AST is involved in the catalysis of the –NH2 amino moieties between aspartate and alpha keto acids, and is found both in the cytoplasm and in the mitochondria. It takes part in the production of energy in the Krebs cycle. AST is an intracellular enzyme and enters the serum as the cell breaks down. The serum level increases with the extent of cellular necrosis. In summary, it is an acute phase indicator of necrosis.



Although aspartate aminotransferase (AST) is produced in the liver, it does not perform liver-specific functions and is found in the heart, skeletal muscle, and kidney. It is also found in the brain, pancreas, and erythrocytes. Serious increases in AST are important for the evaluation vaccine. It can increase at least ten times, usually 20-50 times, up to 100 times.

AST values may also change with exercise, height in body mass index, and age. It is also increased in myocardial infarction, acute liver cell damage, muscular dystrophy, acute pancreatitis, crush type muscle injuries. AST is not used alone in the evaluation, but ALT, which is the other transaminidase enzyme, and other liver enzymes and even other blood tests are evaluated together. The patient’s symptoms and clinic are also an important part of the evaluation. Generally, in ischemia or toxic liver cell damage, AST levels are both earlier and more elevated than ALT levels.

In alcoholic hepatitis, the AST value usually does not exceed 6 times the normal value. If there are other accompanying problems, it may rise even higher.

If the AST value is 2-5 times the normal serum value, possible causes in the patient:

  • Hemolytic anemia
  • Hemolysis
  • Fatty liver
  • Liver metastasized malignancies
  • Drug-related conditions
    • Opiate,
    • Erythromycin,
    • Sulfonamides,
    • Anti TB drugs,
    • Paracetamol,
    • Aspirin,
    • Vitamin A
  • Other reasons
    • Pulmonary embolism,
    • Alcoholic delirium tremens,
    • Acute Pancreatitis,
    • IM injection,
    • Heavy physical exercise.

Possible causes if blood AST value is 10-20 times normal serum level:

  • Severe myocardial infarction
  • Infections
  • Infectious mononucleosis
  • Alcoholic cirrhosis

Possible causes if the blood AST value is more than 20 times the normal serum level:

  • Serious muscle damage (trauma, accidents, crush etc.)
  • Acute viral hepatitis,
  • Toxic hepatitis (drugs etc.),
  • Ischemic hepatitis (severe congestive heart failure etc.),



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