Aspartate aminotransferase (AST or SGOT) is an enzyme (protein) found in several body tissues, particularly the liver and muscles, including the heart muscle. The AST test is mainly used to diagnose and monitor liver disease.
A low AST level has no clinical significance. An abnormally high level indicates that the liver cells or muscles are damaged and releasing their contents into the bloodstream. High AST levels (350 units per litre (U/L) or more) are usually caused by acute viral hepatitis. These high levels generally go back to normal within 1 to 2 months, or in exceptional cases within 3 to 6 months. Extremely high AST levels (often 3,000 U/L or more) indicate toxic impairment of the liver by a drug or poison, or a condition that decreases blood flow through the liver, destroying cells (ischemia). Moderately high AST level (less than 4 times the normal) are found in most other liver diseases (chronic hepatitis, cirrhosis, bile duct obstruction, liver cancer, and so on).
AST levels can also be high in the case of muscular diseases and for a few days after a myocardial infarction (heart attack).