Calcitonin and Fracture Reduction
Calcitonin is a polypeptide hormone that plays a role in the regulation of calcium and bone metabolism, and has direct renal effects and actions on the GI tract. Continuous use of calcitonin is associated with a persistent decrease in the rate of bone resorption, which is associated with decreased resorptive activity and the number of osteoclasts. The Prevent Recurrence of Osteoporotic Fractures (PROOF) trial, the largest randomized controlled trial of nasal calcitonin, demonstrated a reduction in vertebral fractures for those individuals taking 200 IU/d, but there was no significant decline for those receiving 100 or 400 IU/d. Intranasal calcitonin has not been shown to significantly decrease nonvertebral fracture rates after 5 years.⁶⁸