The aspartate aminotransferase test measures the amount of AST in the blood, states Lab Tests Online. AST stands for aspartate aminotransferase, an enzyme found in the liver.
The AST test is used to detect liver injuries, notes Lab Tests Online. This test is often performed in conjunction with the alanine aminotransferase test. Alanine aminotransferase, or ALT, is also a liver enzyme.
A normal AST level ranges from 10 to 34 international units per liter, states MedlinePlus. An elevated AST level is usually an indication that the liver is diseased or damaged. Cirrhosis, liver tumors, pancreatitis, reduced blood flow to the liver and death of the liver tissue can cause elevated AST levels. Because AST is also found in the heart and muscle cells, heart attacks and muscle trauma can cause AST levels to rise. Other causes of an elevated AST level include seizures, burns, surgery, mononucleosis and the use of medications that damage the liver.
A doctor orders an AST test when a patient has the signs or symptoms of a liver problem, explains Lab Tests Online. Weakness, nausea and vomiting, itching, abdominal pain, and yellowing of the skin are all possible signs of liver problems. The test is also used to diagnose and monitor liver problems in people who consume excess amounts of alcohol and those with family histories of liver disease.