Calcitonin is a hormone produced by the thyroid gland that helps regulate calcium levels in the body. It works by lowering blood calcium levels when they are too high, primarily by inhibiting the activity of osteoclasts, the cells responsible for breaking down bone tissue. This action helps maintain bone density and overall bone health. Calcitonin is often used in medical treatments for conditions like osteoporosis and Paget's disease, where bone density is compromised. It can be administered as a nasal spray or injection, providing a way to manage calcium levels and support bone strength in affected individuals.