Definition of AST:

AST (aspartate aminotransferase) is an enzyme found in high amounts in heart muscle and liver 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.

How the test is performed:

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.

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:

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.

An increase in AST levels may be due to:

• Acute kidney failure
• Cirrhosis (scarring of the liver)
• Heart attack
• Hemochromatosis
• Hemolytic anemia
• Hepatitis
• Lack of blood flow to the liver (liver ischemia)
• Liver tumor
• Medicines that are toxic to the liver
• Mononucleosis ("mono")
• Muscle disease or trauma
• Pancreatitis (swollen and inflamed pancreas)

AST levels may also increase after:

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

What the risks are:

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.