Aspartate Aminotransferase (AST/SGOT), Serum

AST is an enzyme primarily found in the cells of the liver. Increased levels of AST are seen when the liver is damaged. Elevated AST levels in not specific to liver pathology. AST testing can be done to monitor treatment for liver diseases or when a person has symptoms suggestive of a liver disorder. Aspartate aminotransferase (AST) test is usually done to detect liver damage. It is often done with alanine aminotransferase (ALT), or as part of a liver function test to screen and diagnose liver disorders. Though AST and ALT are the two most important tests to detect liver injury, ALT is more specific and more commonly increased than is AST. Sometimes AST levels are compared directly to ALT levels and an AST/ALT ratio is usually calculated to distinguish between different causes of liver damage and to differentiate liver injury from heart or muscle damage. AST and ALT levels are often compared with ALP (alkaline phosphatase) levels, Total Protein levels, and serum bilirubin levels to determine which form of liver disease is present in a person. AST and ALT levels are often measured to monitor treatment of persons with liver disease. Sometimes AST and ALT levels may be used to monitor people on drugs which are toxic to liver AST levels increase, then the person may be switched to another medication.

1. Can Liver diseases be asymptomatic?

Yes, early acute liver disease and chronic liver disease often have no symptoms or have mild non-specific symptoms, such as fatigue and nausea.

2. Can abnormal test results indicate a normal liver?

Yes, in many conditions, such as shock, burns, severe infections, muscle trauma, dehydration, pancreatitis, hemolysis, and pregnancy, one or more parameters of the LFT are abnormal.

3. Why is family history important?

In genetically inherited conditions, such as hemochromatosis and Wilson disease, can there is progressive damage to the liver. Early detection of these conditions helps in treatment and further management.

4. What are the other conditions that can increase AST levels ?

Conditions associated with heart and skeletal muscle, can elevate AST levels. Mild to moderate increase may be seen with vigorous exercise, skeletal muscle injury, acute pancreatitis and heart attacks.

5. What are the other tests done to determine the cause of liver damage?

A thorough physical examination and evaluation of person's medical history is done initially. This is followed by tests for hepatitis A, hepatitis B, and hepatitis C, copper and ceruloplasmin levels in Wilson disease, iron tests and genetic tests for hemochromatosis, etc. To know the cause and extent of liver damage, a liver biopsy may be performed.