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 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.
How to Prepare for the Test
No special preparation is needed.
The normal range is 10 to 34 U/L (0.17 to 0.57 µkat/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.
Veins vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Risks associated with having blood drawn are slight, but may include:
- Bleeding from where the needle was inserted
- Fainting or feeling lightheaded
- Hematoma (blood collecting under the skin)
- Infection (a slight risk any time the skin is broken)
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
- 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.
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.
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.
Pincus MR, Tierno PM, Gleeson E, Bowne WB, Bluth MH. Evaluation of liver function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 21.
Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 73.