Updated February 19, 2009.

Definition: Alkaline phosphatase is an enzyme produced naturally within the body. It is mostly made in the liver and bones. When there is breakdown of bone within the body, more alkaline phosphatase is sent into the bloodstream where it can be measured with a simple blood test. Because prostate cancer has a strong preference for spreading to the bones, alkaline phosphatase is an important test to determine if this has happened.