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Alkaline Phosphatase Test

What is the alkaline phosphatase test?

This test measures the amount of a substance called alkaline phosphatase (ALP) in your blood. It is an enzyme found in most tissues, especially in the liver and bones.

Why is this test done?

The amount of ALP in your blood is measured to help diagnose liver and bone disease. The test may also be used to help check medical treatments that can damage the liver or bones.

How do I prepare for this test?

  • You may need to avoid taking certain medicines before the test because they might affect the test result. Make sure your healthcare provider knows about any medicines, herbs, or supplements that you are taking. Don't stop any of your regular medicines without first consulting with your healthcare provider.
  • Talk to your healthcare provider if you have any questions about the test.

How is the test done?

A small amount of blood is taken from your arm with a needle. The blood is collected in tubes and sent to a lab.

Having this test will take just a few minutes of your time.

How will I get the test result?

Ask your healthcare provider when and how you will get the result of your test.

What does the test result mean?

In most labs the normal ALP range for adults is 39 to 117 units per liter (U/L). The normal range may vary from lab to lab. Normal ranges are usually shown next to your results in the lab report.

Your ALP may be higher than normal if:

  • You have a liver infection such as viral hepatitis.
  • You have a blockage in your liver or gallbladder caused by gallstones or a tumor.
  • You have liver disease caused by toxins such as alcohol.
  • Your liver is inflamed because of certain medicines you are taking.
  • You have liver cancer.
  • You have bone cancer or another bone disease.
  • You have a glandular (hormonal) problem.
  • You have kidney disease.
  • Your body needs more vitamin D.
  • You are pregnant.

Because many organs in the body contain ALP, it may be important to know where the increased amount of the enzyme in the blood is coming from. Your healthcare provider may order an ALP isoenzyme test. The ALP isoenzyme test measures different types of ALP in the blood. It can find which organ is causing the increased amount of ALP.

Your ALP may be lower than normal if:

  • Your body is not getting the nutrients it needs from your diet.
  • You have anemia.
  • You have a glandular (hormonal) disorder.

What if my test result is not normal?

Test results are only one part of a larger picture that takes into account your medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your result and ask questions. Ask if and when you need more tests.

Written by Tom Richards, MD, for RelayHealth.
Published by RelayHealth.
Last modified: 2011-06-28
Last reviewed: 2011-06-02
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2011 RelayHealth and/or its affiliates. All rights reserved.
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