Aspartate Aminotransferase (AST)
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.
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
- 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.
An aspartate aminotransferase (AST) test measures the amount of
enzyme in the blood. Results are usually available
within 12 hours.
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 levels of AST may be caused by:
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
- Taking large doses of vitamin A.
- Taking some
herbs and natural products, such as echinacea and
- Injury to a muscle.
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).
different conditions can raise AST blood levels, so other testing is usually
needed to interpret an abnormal AST result.