At a Glance
Why Get Tested?
To screen for or monitor treatment for a liver or bone disorder
When to Get Tested?
As part of liver function tests or when a person has symptoms of a liver or bone disorder
A blood sample taken from a vein in the arm
Test Preparation Needed?
Fasting is preferred but not required for this test
The Test Sample
What is being tested?
Alkaline phosphatase is an enzyme found in high levels in bone and liver. Smaller amounts of ALP are found in the placenta of women who are pregnant, and in the intestines. Each of these body parts makes different forms of ALP. The different forms are called isoenzymes.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Fasting is preferred but not required for this test. Eating a meal can increase the ALP level slightly for a few hours in some people. It is usually better to do the test after fasting overnight. In this case, only water is permitted.
Ask a Laboratory Scientist
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.