Liver enzymes are enzymes that found inside the hepatocytes (liver cells), which are released to the blood circulation when the liver cells are damaged during inflammation or infection by microorganism or parasite.
There are different types of liver enzymes; the first is that group of enzymes that contained inside the hepatocytes only as Aspartate aminotransferase (AST or GOT), Alanine aminotransferase (ALT or GPT), Lactate dehydrogenase (LDH) and Sorbitol dehydrogenase (SDH). The second group including those enzymes that present inside both the hepatocytes and the cells lining the biliary tract as Gamma glutamyltransferase (GGT). The third group include liver enzymes that located inside the the cells lining the biliary tract as Alkaline phosphatase (ALP).
The above classification does not mean that the above enzymes found only in the liver cells, all the above mentioned enzymes except GGT are distributed in other tissues in the body. For example, AST and ALT is released also from skeletal and cardiac muscles, ALP is released also from the intestine, bone and RBCs……etc.
This means that you can not depend on liver enzymes only for diagnosis of a liver disease. Liver enzymes can be used to confirm the clinical examination that suggested the liver dysfunction.