Aspartate Aminotransferase (AST) is an enzyme primarily found in liver and heart tissue, and in smaller amounts in the kidneys and skeletal muscles. In healthy individuals, AST levels are generally low. However, when cellular damage occurs in these tissues, AST levels in the bloodstream can rise significantly. This elevation is used as a valuable indicator, particularly in the diagnosis of conditions such as hepatitis, cirrhosis, and other forms of liver damage.