An alkaline phosphatase (ALP) test measures the amount of the enzyme ALP in the blood. ALP is made mostly in the liver and in bone with some made in the intestines and kidneys. It also is made by the placenta of a pregnant woman.
The liver makes more ALP than the other organs or the bones. Some conditions cause large amounts of ALP in the blood. These conditions include rapid bone growth (during puberty), bone disease (osteomalacia or Paget's disease), or a disease that affects how much calcium is in the blood (hyperparathyroidism), vitamin D deficiency, or damaged liver cells.
If the ALP level is high, more tests may be done to find the cause.
A test for alkaline phosphatase (ALP) is done to:
An alkaline phosphatase test is often done at the same time as a routine blood test. You do not need to do anything before having a routine blood test.
If you are having a follow-up ALP test, you may be asked to not eat or drink for 10 hours before the test. The ALP level generally goes up after eating, especially after eating fatty foods.
Many medicines may change the results of this test. Be sure to tell your doctor about all the non-prescription and prescription medicines you take.
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 will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).
The health professional drawing your blood will:
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.
There is very little chance of a problem from having blood sample taken from a vein.
An alkaline phosphatase (ALP) test measures the amount of the enzyme ALP in the blood.
Normal values may vary from lab to lab.
Less than 350 U/L or less than 5.95 mckat/L
Women in the third trimester of pregnancy have high ALP levels because the placenta makes ALP. Children normally have much higher ALP than adults because rapid bone growth is normal in children and bones make ALP.
Reasons you may not be able to have the test or why the results may not be helpful include:
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Primary Medical Reviewer||Brian D. O'Brien, MD - Internal Medicine|
|Specialist Medical Reviewer||Alan C. Dalkin, MD - Endocrinology|
|Last Revised||September 30, 2010|
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