Aspartate aminotransferase (AST) blood test
The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No special preparation is needed.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
AST is an enzyme found in high levels in the liver, heart, and muscles. It is also found in lesser amounts in other tissues. An enzyme is a protein that causes a specific chemical change in the body.
Injury to the liver results in release of AST into the blood.
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The normal range is 8 to 33 U/L.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
An increased AST level is often a sign of liver disease. Liver disease is even more likely when the levels of substances checked by other liver blood tests have also increased.
An increased AST level may be due to any of the following:
- Scarring of the liver (cirrhosis)
- Death of liver tissue
- Heart attack
- Too much iron in the body (hemochromatosis)
- Swollen and inflamed liver (hepatitis)
- Lack of blood flow to the liver (liver ischemia)
- Liver cancer or tumor
- Use of drugs that are toxic to the liver, especially alcohol use
- Mononucleosis ("mono")
- Muscle disease or trauma
- Swollen and inflamed pancreas (pancreatitis)
AST level may also increase after:
- Burns (deep)
- Heart procedures
Pregnancy and exercise may also cause an increased AST level.
There is little risk involved with having your blood taken. Veins vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Risks associated with having blood drawn are slight, but may include:
- Fainting or feeling lightheaded
- Excessive bleeding
- Multiple punctures to locate veins
- Hematoma (blood collecting under the skin)
- Infection (a slight risk any time the skin is broken)
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Chernecky CC, Berger BJ. Aspartate aminotransferase (AST, aspartate transaminase, SGOT) - serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:172-173.
Daniels L, Khalili M, Goldstein E, Bluth MH, Bowne WB, Pincus MR. Evaluation of liver function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 22.
Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease: Pathophysiology/Diagnosis/Management. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 73.