An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. AST is normally found in red blood cells, liver, heart, muscle tissue, pancreas, and kidneys. AST formerly was called serum glutamic oxaloacetic transaminase (SGOT).

Low levels of AST are normally found in the blood. When body tissue or an organ such as the heart or liver is diseased or damaged, additional AST is released into the bloodstream. The amount of AST in the blood is directly related to the extent of the tissue damage. After severe damage, AST levels rise in 6 to 10 hours and remain high for about 4 days.

The AST test may be done at the same time as a test for alanine aminotransferase, or ALT. The ratio of AST to ALT sometimes can help determine whether the liver or another organ has been damaged. Both ALT and AST levels can test for liver damage.

Why It Is Done

An aspartate aminotransferase (AST) test is done to:

• Check for liver damage.
• Help identify liver disease, especially hepatitis and cirrhosis. Liver disease may produce symptoms such as pain in the upper abdomen, nausea, vomiting, and sometimes jaundice.
• Check on the success of treatment for liver disease.
• Find out whether jaundice was caused by a blood disorder or liver disease.
• Keep track of the effects of cholesterol-lowering medicines and other medicines that can damage the liver.

How To Prepare

To prepare for an aspartate aminotransferase (AST) test:

• Avoid strenuous exercise just before having this test done.

Tell your doctor if you:

• Are taking any medicines. Many medicines can interfere with test results. Your doctor may instruct you to stop taking certain medicines for several days before having an AST test. Some herbs and natural products (such as echinacea and valerian) also can affect AST results.
• Are allergic to any medicines.
• Are or might be pregnant.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?) .

How It Is Done

The health professional taking a sample of your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure on the site and then put on a bandage.