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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.

This test is mainly done along with other tests (such as ALT, ALP, and bilirubin) to diagnose and monitor liver disease.

Normal Results

The normal range is 10 to 34 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 usually 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:

AST level may also increase after:

  • Burns (deep)
  • Heart procedures
  • Seizure
  • Surgery

Pregnancy and exercise may also cause an increased AST level.


Veins vary in size from one patient 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)

Alternative Names

Aspartate aminotransferase; Serum glutamic-oxaloacetic transaminase; SGOT


Pincus MR, Tierno PM, Fenelus M, Bowne WB, Bluth MH. Evaluation of liver function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011: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: Pathophysiology/Diagnosis/Management. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 73.

Update Date 2/8/2015

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