Liver blood tests are designed to show evidence that abnormalities, for example, inflammation, liver cell damage, has or is occurring within the liver.The blood tests most frequently used for liver disease are the aminotransferases (alanine aminotransferase or ALT and aspartate aminotransferase or AST).Normal levels of ALT ranges from about 7-56 units/liter, and 10-40units/liters for AST.Elevated levels of AST and ALT may signify the level of liver damage in a person.Common causes of elevated ALT and AST areheart failure.

Many drugs may cause elevated AST, and ALT and some medications can cause severe damage (for example, acetaminophen [Tylenol liver damage]).Less common causes of abnormal AST and ALT levels are wide ranging (for example, toxins, and autoimmune diseases)People with mild to moderate elevations of AST and ALT with no or few symptoms should follow-up with their doctor for potential underlying causes of elevated AST and/or ALT.Repeated test levels (monitoring) is useful in some patients (for example, viral-caused and Tylenol-caused elevations) to guide therapeutic treatments.Other liver enzymes, although not measured routinely, may add additional information about liver functions.