Alkaline phosphatase in serum consists of 4 structural genotypes: liver-bone-kidney, intestinal, and placental types, and the variant from the germ cells. It is found in osteoblasts, hepatocytes, leukocytes, the kidneys, spleen, placenta, prostate, and the small intestine. The liver-bone-kidney type is particularly important.A rise in the alkaline phosphatase occurs with all forms of cholestasis, particularly with obstructive jaundice. It is also elevated in diseases of the skeletal system, such as Paget disease, hyperparathyroidism, rickets, and osteomalacia, as well as with fractures and malignant tumors.