Calcitonin is a small peptide hormone, a member of the calcitonin family which is encoded by the CALC-1 gene. Calcitonin plays an important role in regulating calcium and phosphorus metabolism and is primarily synthesized in parafollicular cells of the thyroid gland from pre-procalcitonin. After removal of the signal peptide, procalcitonin undergoes proteolytic cleavage to form Calcitonin. Cleaved immature calcitonin is further processed into the mature form, which is stored in secretory granules within the cell. Secretion of calcitonin is stimulated by elevated levels of calcium ions in the blood. Calcitonin rapidly lowers the level of calcium and phosphate in blood by promoting the incorporation of these ions in the bones. Studies show that a high level of serum calcitonin is associated with medullary thryroid cancer and is widely used as biomarker for this type of carcinoma.