The aspartate aminotransferase (AST) test measures the activity of an enzyme found in the liver, heart, and other tissues, and is used to check for damage to these organs. It is primarily used to test for liver damage and monitor the treatment of liver disorders, but can also indicate muscle disorders and heart problems. Elevated levels may be caused by various factors, and further diagnostic workup is usually required.
Aspartate aminotransferase is a type of enzyme usually found in the liver and heart, the activity of which is measured in a laboratory test to check for damage to these organs. It is also commonly known as aspartate transaminase. The aspartate aminotransferase (AST) test can be used specifically to check for liver or heart problems, or it can be part of a standard medical screening.
The liver has a number of aminotransferases, but the ones used in medical testing are alanine aminotransferase and aspartate aminotransferase. AST is found in multiple places in the body and can be used as an indicator of more problems. Alanine aminotransferase is generally found only in the liver.
In addition to being found in the liver, aspartate aminotransferase is also found in skeletal and cardiac tissue. In healthy tissue, AST is found within cells and is present only at low levels in blood serum. If the tissue is damaged, however, this enzyme leaks into the blood serum and is found at elevated levels.
The AST test was previously used in cardiology to diagnose heart attacks, but has since been supplanted by other tests. Muscle disorders are another area where AST levels can be elevated. This includes Duchenne muscular dystrophy and a condition known as myositis.
The primary use of the AST test, however, is to test for liver damage and monitor the treatment of liver disorders. It is a highly reliable marker for liver abnormalities. Low elevations in AST levels are difficult to interpret, as they could indicate a serious disorder or be benign. For example, if a person drinks an alcoholic beverage a few hours before a blood draw, that beverage can cause AST levels to rise.
Lower levels of AST elevation may be due to alcohol combined with acetaminophen, such as Tylenol®. Common medications such as statins, aspirin, antibiotics, and narcotics can also cause slightly high levels. Very high levels are usually an indication of severe liver damage, such as hepatitis or necrosis. Another reason for high levels can be shock. Moderately high levels may be due to long-term liver disease, such as cirrhosis or alcohol abuse.
Because so many factors can cause small elevations in AST levels, an increased level will usually warrant further diagnostic workup. This test is also used to analyze whether liver disease is being treated successfully. If the levels are decreasing, it could indicate that the liver is recovering. The sgot test is an older name for this test, referring to the older glutamate oxaloacetate transaminase (sgot) name for AST.
Aspartate aminotransferase is one of several different enzymes that transfers one amino acid to another compound. Amino acids are the components of proteins. They contain an NH2 amino group on them. This type of reaction is important for the protein metabolism of the cell.
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