AST Test (Aspartate Aminotransferase)

Reviewed

Also called: SGOT test, serum glutamic oxaloacetic transaminase test, aspartate transaminase test

An AST blood test measures the amount of AST (aspartate aminotransferase) in your blood. It is commonly used to help diagnose liver damage or disease. AST is an enzyme found mainly in your liver but also in your heart, muscles, and other tissues. When liver or other cells that contain AST are damaged, they release AST into your blood, leading to high levels.

Specimen: blood

Why this test may be ordered

  • As part of a routine blood screening to check the health of your liver
  • To help diagnose or monitor liver problems
  • To help diagnose other health conditions
  • If you have symptoms of liver damage (nausea, vomiting, lack of appetite, fatigue, weakness, jaundice, abdominal swelling/pain, ankle/leg swelling, dark urine, light-colored stool, frequent itching)
  • If you are at higher risk for liver disease due to family history, alcohol use disorder, obesity, diabetes, certain medicines, hepatitis, or exposure to hepatitis

Preparation and collection

You may need to stop taking certain medicines before the test; tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to. An AST test is usually ordered with other blood tests, and you may need to fast (not eat or drink) for up to 12 hours before these tests. Your provider will let you know if there are any special instructions.

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. This usually takes less than five minutes.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

Understanding results

Low levels of AST in the blood are usually considered normal. High levels of AST in the blood may be due to liver disease or other liver problems. If your results are not in the normal range, it doesn't always mean that you have a medical condition that needs treatment. Many things can affect your results, such as pregnancy, exercise, certain medicines, and your age or sex. Talk with your provider to learn what your results mean.

  • Low AST level: Usually considered normal. Limitation: Many things can affect your results, such as pregnancy, exercise, certain medicines, and your age or sex. Talk with your provider to learn what your results mean. Next step: Your provider will interpret your results in the context of your overall health.
  • High AST level: May be due to liver disease or other liver problems. Other reasons can include hepatitis, cirrhosis, mononucleosis, heart procedures or problems, pancreatitis, hemochromatosis, deep burns, seizures, use of drugs that are toxic to the liver (especially alcohol use), or surgery. Limitation: Many things can affect your results, such as pregnancy, exercise, certain medicines, and your age or sex. A high level does not always mean you have a medical condition that needs treatment. Talk with your provider to learn what your results mean. Next step: Your provider may order an ALT blood test along with your AST test. If you have high levels of AST and/or ALT, it may mean that you have some type of liver damage.
  • Many things can affect your results, such as pregnancy, exercise, certain medicines, and your age or sex.
  • A result that is not in the normal range does not always mean that you have a medical condition that needs treatment.
  • The test is not diagnostic by itself; it is often part of a group of liver function tests.

What to do next

Talk with your provider to learn what your results mean. Your provider may order an ALT blood test along with your AST test. If you have high levels of AST and/or ALT, it may mean that you have some type of liver damage.

  • What do my AST results mean in my specific situation?
  • Do I need any follow-up tests, such as an ALT test or other liver function tests?
  • Should I make any changes to my medicines or lifestyle based on these results?

Evidence source

U.S. National Library of Medicine: AST Test (Aspartate Aminotransferase)

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