Aspartate Aminotransferase (AST)

An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. Results are usually available within 12 hours.

Normal

Normal values may vary from lab to lab.

High values

Very high levels of AST may be caused by:

• Recent or severe liver damage, such as hepatitis caused by a viral infection or drug reaction.
• Decay of a large tumor (necrosis).
• Shock.

Moderately high levels of AST may be caused by:

• Long-term (chronic) diseases that affect the liver, such as cirrhosis.
• A heart attack or heart failure.
• Alcohol abuse.
• Having taken high doses of vitamin A.
• Kidney or lung damage.
• Mononucleosis.
• Duchenne muscular dystrophy.
• Some types of cancer.
• A rare autoimmune disease that affects muscles (myositis).

Slightly high levels of AST may be caused by:

• Fatty deposits in the liver.
• Many medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates.
• Alcohol abuse. People who drink excessive amounts of alcohol and take acetaminophen (such as Tylenol) can have high AST blood levels.

AST levels may be high when a disease first develops, which is often when tissue damage is most severe. Decreasing levels of AST in the blood may be a sign of recovery from the disease or injury.

Many other conditions, including severe burns, traumatic injuries, pulmonary embolism, or heat exhaustion and heatstroke, and ingestion of poisonous mushrooms may cause elevated AST levels.