Causes of high alkaline phosphatase include bone growth, healing fracture, acromegaly, osteogenic sarcoma, liver or bone metastases, leukemia, myelofibrosis, and rarely myeloma. Alkaline phosphatase is used as a tumor marker
Additional Test Information:
Serum alkaline phosphatase is a member of a family of zinc metalloprotein enzymes that function to split off a terminal phosphate group from an organic phosphate ester. This enzyme functions in an alkaline environment (optimum pH of 10). Active center of ALP enzymes includes a serine residue. Mg and Zn ions are required for minimal activity. Enzyme activity is localized in the brush border of the proximal convoluted tubule of the kidney, intestinal mucosal epithelial cells, hepatic sinusoidal membranes, vascular endothelial cells and osteoblasts of bone. There are distinctive forms of ALP in the placenta and small intestine; hepatic, renal and osteoblast (bone) ALP are similar molecules.
Serum (preferred) or plasma
Red-top tube, gel-barrier tube, or green-top (heparin) tube
Separate serum or plasma from cells within 45 minutes of collection. If a red-top tube or green-top tube is used, transfer separated serum or plasma to a plastic transport tube.
Hemolysis; plasma specimen; specimen collected in EDTA tube; improper labeling