calcitonin UK /ˌkæl.sɪˈtəʊ.nɪn/US /ˌkæl.sɪˈtoʊ.nɪn/ noun2 •A polypeptide hormone secreted by the thyroid gland that has the effect of lowering blood calcium.Intriguingly, the rat C1b isoform of the calcitonin receptor (CTR) (see Section VI-B) has very little interaction with the thyroidally derived form of calcitonin. — 1997 •A synthetic or recombinant form of calcitonin used to treat Paget disease of bone and postmenopausal osteoporosis. formscalcitonins
