Digestive Disorders Health Center

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having blood sample taken from a vein.

• You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
• In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
• Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.

Results

An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. Results are usually available within 12 hours.

Normal

The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what?s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

High values

High levels of AST may be caused by:

• Liver damage from conditions such as hepatitis or cirrhosis.
• Decay of a large tumor (necrosis).
• A heart attack or heart failure.
• Many medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates.
• Having taken high doses of vitamin A.
• Kidney or lung damage.
• Mononucleosis.
• Some types of cancer.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Taking medicines. Talk with your doctor about all the prescription and nonprescription medicines you are taking. You may be instructed to stop taking your medicines for several days before the test.
• Taking large doses of vitamin A.
• Taking some herbs and natural products, such as echinacea and valerian.
• Injury to a muscle.
• Recent cardiac catheterization or surgery.

What To Think About

• The aspartate aminotransferase (AST) test is more effective than the alanine aminotransferase (ALT) test for detecting liver damage caused by alcohol abuse. The AST to ALT ratio may sometimes help determine if liver damage is related to alcohol dependence. For more information, see the topic Alanine Aminotransferase (ALT).
• Many different conditions can raise AST blood levels, so other testing is usually needed to interpret an abnormal AST result.