Reasons, Procedure & Preparation For Blood Alkaline Phosphatase Test

Submitted on March 27, 2012

Alkaline Phosphatase In Blood Test

An alkaline phosphatase in blood test is usually used to gauge the levels of the enzyme alkaline phosphatase in the body. While the normal values of the enzyme may vary from lab to lab, the generally accepted standards read at about 30 to 126 units per liter in adults and about 30 to 300 units per liter in children. Women that are in the third trimester of a pregnancy will tend to have higher levels of alkaline phosphatase because the placenta is a major producing agent of the enzyme. Higher levels of the enzyme that are of more concern are usually the result of liver problems such as hepatitis, gallstones, liver cancer, cirrhosis and cancer that has spread to the liver from another part of the body. Bone diseases such as Paget's disease, rickets and bone tumors can also have a significant contribution to heightened alkaline phosphatase levels. Low alkaline phosphatase blood test will usually be a sign of malnutrition and like celiac disease or a lack of nutrients such as scurvy.

Reason Why It is Performed

A blood test alkaline phosphatase is performed to check for any liver disease or damage to the liver. It may also be used to identify any damage being caused to liver by the administration of certain medications. The test is also commonly used to follow up and check on the effectiveness of certain treatments such as in the case of Paget's disease. When there is evidence of liver disease accompanied by high alkaline phosphatase levels, this is generally a sign of blocked bile ducts. The heightened levels of ALP will often allow any cancer to spread to the liver or bones and a blood test alkaline phosphatase will help identify if this has already happened. In most labs, the test is usually a part of a routine set of tests known as the liver panel.  If the doctor is unsure of the cause of the heightened Alp levels, a ALP isoenzyme test may also be ordered.


Since an alkaline phosphatase in blood test is usually taken around the time of a routine blood test, no special preparation is required. However, if you are undergoing a follow up ALP test, you may be asked to avoid consumption of any food or drink for about 10 hours prior to the test. This is mainly because of the fact that the ALP levels are generally higher after eating - especially if the meal consisted of a lot of fatty foods. Moreover, it is essential that you also let your doctor know of any medication you are on, prescription or non prescription, as a number of them have the ability to alter your test results.


As with any blood test, an alkaline phosphatase in blood test requires the drawing of some amount of blood from the vein behind the elbow via a syringe.