Aspartate aminotransferase (AST) blood test
The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood.
How is the Test Performed?
A blood sample is needed.
Preparation 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 is the Test 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.
Normal Results for Aspartate aminotransferase (AST) blood test
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:
- 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.
Aspartate aminotransferase (AST) blood test Risks
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)
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.
|Review Date: 2/8/2015
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.