Alanine Aminotransferase (ALT)
An alanine aminotransferase (ALT) test measures the amount of this
enzyme in the blood. ALT is found mainly in the liver,
but also in smaller amounts in the
heart, muscles, and
pancreas . ALT was formerly called serum glutamic
pyruvic transaminase (SGPT).
ALT is measured to see if the liver is damaged or diseased. Low
levels of ALT are normally found in the blood. But when the liver is damaged or
diseased, it releases ALT into the bloodstream, which makes ALT levels go up.
Most increases in ALT levels are caused by liver damage.
The ALT test is often done along with other tests that check for
liver damage, including aspartate aminotransferase (AST), alkaline phosphatase,
lactate dehydrogenase (LDH), and bilirubin. Both ALT and AST levels are
reliable tests for liver damage.
Why It Is Done
The alanine aminotransferase (ALT) test is done to:
- Identify liver disease, especially
hepatitis caused by alcohol, drugs, or
- Help check for liver damage.
- Find out whether
jaundice was caused by a blood disorder or liver
- Keep track of the effects of
cholesterol-lowering medicines and other medicines
that can damage the liver.
How To Prepare
Avoid strenuous exercise just before having an ALT test.
Tell your doctor if you:
- Are taking any medicines. Many medicines can
interfere with test results. Your doctor may instruct you to stop taking
certain medicines for several days before having an ALT test. Some
herbs and natural products (such as echinacea and
valerian) also can affect ALT results.
allergic to any medicines.
- Are or might be
Talk to your doctor about any concerns you have regarding the need
for the test, its risks, how it will be done, or what the results may mean. To
help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
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.