Alanine Aminotransferase (ALT): About This Test

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What is it?

Location of the liver

An alanine aminotransferase (ALT) test measures the amount of the enzyme ALT in the blood. ALT is found mainly in the liver. When ALT levels are higher than normal, it can mean that the liver is damaged or diseased.

Why is this test done?

The ALT test is done to:

  • Identify liver disease, such as 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 can you prepare for the test?

  • In general, you don't need to prepare before having this test. Your doctor may give you some specific instructions.

What happens during the test?

  • A health professional takes a sample of your blood.

What else should you know about the test?

  • Your results will include an explanation of what a "normal" result is. This is called a "reference range." It is just a guide. 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 may still be normal for you.
  • Many different conditions can raise ALT blood levels, so other testing is usually needed to interpret an abnormal ALT result.

How long does the test take?

  • The test will take a few minutes.

What happens after the test?

  • You will probably be able to go home right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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