• Diseases&Conditions
• Procedures & Tests
• Injuries & Symptoms
• Special Topics
• Nutrition

This test measures the levels of the enzyme, aspartate aminotransferase (AST), in the blood. Enzymes help drive chemical reactions in the body.

Who is a candidate for the test?

Diseases of the liver can cause liver cells to release this enzyme into the bloodstream. Therefore, this test is usually performed to help diagnose liver disorders. AST can also be released by heart, muscle, and brain cells that have been damaged, therefore, this test may be ordered to help diagnose disorders in those organs as well.

How is the test performed?

A blood sample needs to be taken in order to measure the level of AST. The blood is usually drawn from a vein in the forearm or the hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A very thin needle is gently inserted into a vein and the tourniquet is removed. Blood flows from the vein through the needle and is collected in a syringe or vial. The sample is sent to the lab to be analyzed. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.

What is involved in preparation for the test?

Individuals should check with their healthcare professionals for specific instructions on how to prepare for this test.

What do the test results mean?

Normally, the levels of AST in the blood range from 10 to 34 international units per liter (IU/L).

Greater than normal levels of AST may indicate:

• acute hemolytic anemia, which is the breakdown of red blood cells by the body's own defense system.
• acute pancreatitis, an inflammation of the pancreas.
• acute renal failure, a loss of kidney function.
• cirrhosis of the liver, which is scarring and loss of liver function.
• death of liver tissue, called liver necrosis.
• hepatitis (liver inflammation).
• infectious mononucleosis, known as the "kissing disease." This disease is an infection caused by the Epstein-Barr virus.
• cancer of the liver.
• multiple trauma, or injuries to several organ systems.
• heart attack.
• primary muscle disease, which are various disorders affecting the muscles.
• progressive muscular dystrophy, which is an inherited, progressive muscle weakness.
• recent cardiac catheterization, a test to see the heart's arteries, or angioplasty, a procedure to relieve narrowing in heart's arteries.
• recent convulsions or seizure disorder.
• recent surgery.
• severe burns.
• muscle injury.

It is generally possible to narrow down this list quickly from the history and physical examination.