Alternative Names alkaline phosphatase, serum alkaline phosphatase, alkaline phosphatase, total
Definition This test measures an enzyme called alkaline phosphatase (ALP) in the blood. ALP occurs in all tissues, especially liver and bone. Diseased or damaged tissues release ALP into the blood.
Who is a candidate for the test? The alkaline phosphatase test is often used to help diagnose certain liver diseases and bone disorders.
How is the test performed? To measure serum levels of ALP, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This restricts blood flow in the veins in the lower arm and enlarges them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle, and is collected in a vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
What is involved in preparation for the test? The doctor will provide specific instructions. Generally, no preparation is required.
What do the test results mean? Normal levels of ALP vary depending on the age and sex of the person, as well as the type of test used.
Author: David T. Moran, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 6/06/2005 Contributors Potential conflict of interest information for reviewers available on request
