AST (aspartate aminotransferase) is an enzyme found in high amounts in liver, heart, and muscle cells. It is also found in lesser amounts in other tissues.
This article discusses the test to measure the amount of AST in the blood.
A blood sample is needed. It is usually taken from a vein. This is called a venipuncture
.
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is mainly done along with other tests (such as ALT, ALP, and bilirubin) to diagnose and monitor liver disease.
Normal Values
The normal range is 10 to 34 IU/L.
Note: IU/L = international units per liter
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results mean
Increased AST levels are usually a sign of liver disease. Liver disease is even more likely if other liver-related blood tests are abnormal.
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 light-headed
Hematoma (blood collecting under the skin)
Infection (a slight risk any time the skin is broken)
Special considerations
AST levels may rise during pregnancy and after exercise.
References
Berk P, Korenblat K. Approach to the patient with jaundice or abnormal liver tests. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 149.
Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier;2010:chap 73.
Review Date:
1/21/2013
Reviewed By:
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.
