Like all enzymes, it is needed, in small amounts, to trigger specific chemical reactions. When it is present in large amounts, it may signify bone or liver disease or a tumor. Purpose Medical testing of alkaline phosphatase is concerned with the enzyme that is found in liver, bone, placenta, and intestine. In a healthy liver, fluid containing alkaline phosphate and other substances is continually drained away through the bile duct. In a diseased liver, this bile duct is often blocked, keeping fluid within the liver.
Alkaline phosphatase accumulates and eventually escapes into the bloodstream.
Its origin differs from that of other enzymes called aminotransferases. Growing bones need alkaline phosphatase. Any condition of bone growth will cause alkaline phosphatase levels to rise. During pregnancy , alkaline phosphatase is made by the placenta and leaks into the mother's bloodstream. This is normal.