Aspartate Aminotransferase (AST) is an enzyme that promotes transfer of an amino group from glutamic acid to oxaloacetic acid. It is found mostly in the liver and heart, and to a lesser extent in other muscles, pancreas, and kidneys. This test is ordered to evaluate a patient who seems to have symptoms of liver disorder since the amount of AST in the blood is directly related to the extent of tissue damage. VERY HIGH levels of AST are usually due to acute hepatitis, or necrosis. MODERATETLY HIGH levels may be caused by heart failure, alcohol abuse, kidney damage, mononucleosis, Duchenne muscular dystrophy, and myositis. SLIGHTLY HIGH levels may be caused by fatty deposits in the liver, or the use of certain drugs such as statins, antibiotics, chemotherapy, aspirin…etc. DECREASED levels are seen in patients undergoing renal dialysis or those with vitamin B6 deficiency. Unexplained AST elevations should first be investigated with ALT and GGT.