What is an AST Test?
AST (aspartate aminotransferase) is an enzyme that is found mostly in the liver, but it's also in muscles and other organs in your body. When cells that contain AST are damaged, they release the AST into your blood. An AST blood test measures the amount of AST in your blood. The test is commonly used to help diagnose liver damage or disease.
Other names: SGOT test, serum glutamic oxaloacetic transaminase test; aspartate transaminase test
What is it used for?
An AST blood test is often part of a routine blood screening to check the health of your liver. The test may help diagnose or monitor liver problems. It may also help diagnose other health conditions.
Why do I need an AST blood test?
You may get an AST blood test as part of your routine checkup or if you have symptoms of liver damage. These may include:
- Nausea and vomiting
- Lack of appetite
- Jaundice, a condition that causes your skin and eyes to turn yellow
- Swelling and/or pain in your abdomen (belly)
- Swelling in your ankles and legs
- Dark-colored urine (pee) and/or light-colored stool (poop)
- Frequent itching
Even if you don't have symptoms, your health care provider may order an AST blood test if you're more likely to develop liver disease because of:
What happens during an AST blood test?
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. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don't need any special preparations for an AST blood test. But an AST test is usually ordered with other blood tests. You usually 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 to follow.
Are there any risks to the test?
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.
What do the results mean?
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 certain medicines and your age, sex, and diet. To learn what your results mean, talk with your provider.
Learn more about laboratory tests, reference ranges, and understanding results.
Is there anything else I need to know about an AST blood test?
Your health care provider may order an ALT blood test with your AST blood test. ALT stands for alanine transaminase, which is another type of liver enzyme. If you have high levels of AST and/or ALT, it may mean that you have some type of liver damage.
You may also have an AST test as part of a group of liver function tests that measure ALT, and other enzymes, proteins, and substances in the liver.
- American Liver Foundation. [Internet]. New York: American Liver Foundation; c2017. Diagnosing Liver Disease – Liver Biopsy and Liver Function Tests; [updated 2020 Feb 17; cited 2022 Feb 14]; [about 3 screens]. Available from: https://liverfoundation.org/for-patients/about-the-liver/diagnosing-liver-disease/
- Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Aspartate Aminotransferase; p. 68–69.
- National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [cited 2022 Feb 14]; [about 15 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
- Testing.com [Internet]. Seattle (WA).: OneCare Media; c2022. Aspartate Aminotransferase: The Test; [modified 2021 Nov 9; cited 2022 Feb 14; [about 14 screens]. Available from: https://www.testing.com/test/aspartate-aminotransferase-ast/
- University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2017. Health Encyclopedia: Aspartate Transaminase; [cited 2017 Mar 13]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=aspartate_transaminase