Alkaline phosphatase is an enzyme present in almost all weaves of the organism, being particularly high in bone, liver, placenta, intestine and kidney. Both increases and decreases of plasma ALP are of importance clinically. Causes of increased plasma ALP: Paget’s disease of bone, obstructive liver disease, hepatitis, hepatotoxicity caused by drugs or osteomalacia. Causes of decreased plasma ALP: Cretinism and vitamin C deficiency. Clinical diagnosis should not be made on a single test result; it should integrate clinical and other laboratory data.