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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 kidneys camera.gif, heart, muscles, and pancreas camera.gif. 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 cirrhosis and hepatitis caused by alcohol, drugs, or viruses.
  • Help check for liver damage.
  • Find out whether jaundice was caused by a blood disorder or liver disease.
  • 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.
  • Are allergic to any medicines.
  • Are or might be pregnant.

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 alcohol.
  • Put the needle into the vein. More than one needle stick may be needed.
  • Attach a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • 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 bandage.

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.

WebMD Medical Reference from Healthwise

Last Updated: November 04, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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