A blood sample is needed. For information on how this is done, see: 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.
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
Diseases that affect liver cells increase the levels of AST. However, increased levels of AST alone do not diagnose liver disease. Measuring ALT at the same time can help narrow the cause of the abnormal test results.
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)
AST levels may rise during pregnancy and after exercise.
Berk PD, Korenblat KM. Approach to the patient with jaundice or abnormal liver test results. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 150.
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.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.