Calcitonin is secreted by

Calcitonin is a polypeptide hormone secreted by the parafollicular or C cells of the thyroid gland; it is involved in plasma calcium homeostasis and acts to decrease the rate of bone resorption. Preparations of calcitonin are called either calcitonin-human or calcitonin-salmon; the former is a synthetic polypeptide with the same sequence as that occurring naturally in humans, and the latter is either derived from salmon or is a synthetic polypeptide of the same sequence as that found in salmon. They are used in the treatment of severe hypercalcemia, Paget&;s disease of bone, and postmenopausal osteoporosis. Ref: Ganong&;s review of medical physiology; 24th edition; page no:-377