Alkaline Phosphatase Test

What is the alkaline phosphatase test?

This test measures the amount of the enzyme alkaline phosphatase in your blood. This enzyme is present in most tissues but is especially concentrated in the liver and bones.

Why is this test done?

The amount of alkaline phosphatase in your blood is measured to help diagnose liver and bone disease. This test may also be used to help check medical treatments that may cause damage to 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 health care provider knows about any medicines, herbs, or supplements that you are taking.
• Talk to your health care provider if you have any questions.

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. There is no risk of getting AIDS, hepatitis, or any other blood-borne disease from this test.

How will I get the test result?

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

What does the test result mean?

In most labs the normal alkaline phosphatase range for adults is 39 to 117 units per liter (U/L). The normal range may vary from lab to lab. The way alkaline phosphatase is measured varies more than for most other blood tests, so check the normal reference range from your lab when you see your result. Normal ranges are usually shown next to your results in the lab report.

Your alkaline phosphatase level may 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 a bone disease.
• You have a glandular (hormonal) disorder.
• Your body needs more vitamin D.
• You have kidney disease.
• You have bone cancer.
• You are pregnant.

Because many organs in the body contain alkaline phosphatase, it is sometimes important to know where the increased amount of the enzyme in the blood is coming from. Your health care provider may order an isoenzyme test, which can identify which specific organ the increased amount of alkaline phosphatase in the blood is coming from.

Your alkaline phosphatase level 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.
• You have a certain rare, inherited genetic defect.

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 health care provider about your result and ask questions.

If your test results are not normal, ask your health care provider:

• if you need additional tests
• what you can do to work toward a normal value
• when you need to be tested again.