ASAT, also known as aspartate aminotransferase, is an enzyme found primarily in the liver and heart. When there is damage to either of them, ASAT is released into the bloodstream.
Since ASAT also exists in other tissues such as kidneys, muscles and pancreas, there will always be small circulating amounts of ASAT. The extent of damage to tissue is directly related to the level of ASAT in blood. If the underlying reason is alcohol, this can be revealed by measuring ALAT at the same time and looking at the ratio between the two.
Normal levels of ASAT indicate a healthy and well functioning liver.
ASAT is therefore primarily measured to assess the extent of liver damage, no matter the underlying cause. Common conditions where ASAT is frequently measured as a means to monitor progress of disease or treatment are hepatitis and cirrhosis. ASAT levels are also measured to identify liver disease and evaluate possible side effects of preventative and curative measures that might damage liver tissue.
High ASAT levels indicate that there is damage to the liver or heart.
Examples of conditions that can cause an increase are chronic alcohol use, heart attacks, hepatitis, liver cirrhosis and pulmonary embolism. Elevated levels can also be found after muscle injury and certain medications or supplements which are metabolized by or toxic to the liver.
Low ASAT levels are considered within the normal range and no need for concern.
Extremely low levels however, may indicate conditions including vitamin B6 deficiency or severe liver damage to the extent that the liver cannot produce ASAT. If a severe liver damage would be the underlying cause for low ASAT levels, other associated symptoms and several deviating test results would accompany that reduced ASAT.