The liver is located in the right upper portion of the abdominal cavity just beneath the rib cage. The liver has many functions that are vital to life. Briefly, some of the important functions of the human liver are:
Liver blood tests are some of the most commonly performed blood tests. These tests can be used to assess liver functions or liver injury. An initial step in detecting liver damage is a simple blood test to determine the level of certain liver enzymes (proteins) in the blood. Under normal circumstances, these enzymes mostly reside within the cells of the liver. But when the liver is injured for any reason, these enzymes are spilled into the blood stream. Enzymes are proteins that are present throughout the body, each with a unique function. Enzymes help to speed up (catalyze) routine and vital chemical reactions in the body.
Among the most sensitive and widely used liver enzymes are the aminotransferases. They include aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT). These enzymes are normally predominantly contained within liver cells and to a lesser degree in the muscle cells. If the liver is injured or damaged, the liver cells spill these enzymes into the blood, raising the AST and ALT enzyme blood levels and signaling liver disease.
Other blood tests pertaining to the liver are measurements of some of the other enzymes found the liver. In addition to AST and ALT, alkaline phosphatase, 5' nucleotidase, and gamma-glutamyl transpeptidase (GGT) are a few of the other enzymes located in the liver. The focus of this article is mainly on the most common liver enzymes, AST and ALT.