Alkaline phosphatase (ALP) is present as a number of isoenzymes (different forms of ALP) and is found in the highest concentrations in bone, liver, kidney, intestine and placenta.
The activity of ALP found in serum is a composite of isoenzymes from those sites. The structure of the enzyme depends on where in the body it is produced. ALP is used for diagnosis and monitoring treatment of liver, bone, intestinal and parathyroid diseases.