Liver function tests help determine the health of your liver by measuring the levels of proteins, liver enzymes, or bilirubin in your blood. 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.
A liver function test is done to remove contaminants from your blood, convert nutrients from the foods you eat, store minerals and vitamins, regulate blood clotting, produce proteins, enzymes, and bile, make factors that fight infection, remove bacteria from your blood, process substances that could harm your body, and maintain hormone balances.
Typically the range for normal AST is reported between 10 to 40 units per liter and ALT between 7 to 56 units per liter. Mild elevations are generally considered to be 2-3 times higher than the normal range. In some conditions, these enzymes can be severely elevated, in the 1000s range.