The serum aspartate aminotransferase (AST) test, formerly known as SGOT, measures the intracellular level of this enzyme. It is found in high concentrations in liver cells, heart muscle, skeletal muscle, kidneys, and brain cells. It is released into the bloodstream when the membranes of these cells are damaged. It is primarily used as part of a liver function test to help diagnose and monitor liver diseases, but it is not specific to the liver alone.