Diseases & Conditions

Alkaline Phosphatase - ALP


Overview & Description

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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.


Preparation & Expectations

What is involved in preparation for the test?

The healthcare provider will provide specific instructions. Generally, no preparation is required.


Results and Values

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.

Higher levels of ALP than normal may indicate:

  • liver disease
  • bone disease
  • leukemia, a cancer of the blood and bone marrow
  • various hormone problems
  • pregnancy
  • Lower levels of ALP than normal may indicate:

  • anemia, or a low red blood cell count
  • malnutrition
  • various hormone problems

  • Attribution

    Author:David T. Moran, MD
    Date Written:
    Editor:Duff, Ellen, BA
    Edit Date:04/11/00
    Reviewer:Adam Brochert, MD
    Date Reviewed:09/20/01