Description

Calcitonin is a hormone produced by the parafollicular cells (also known as C cells) of the thyroid gland. It plays a role in calcium homeostasis, which is the maintenance of stable calcium levels in the blood.

The primary function of calcitonin is to regulate calcium levels by inhibiting the breakdown of bone, which helps to lower blood calcium levels. It does this by reducing the activity of osteoclasts, cells responsible for breaking down bone tissue and releasing calcium into the bloodstream. By inhibiting osteoclast activity, calcitonin helps to promote bone formation and maintain bone density.

Calcitonin secretion is stimulated by high levels of calcium in the blood, particularly after meals when calcium absorption from the intestines increases. Additionally, calcitonin can be released in response to stress or certain medications.

Although calcitonin plays a role in calcium regulation, its overall significance in maintaining calcium homeostasis in adults is relatively minor compared to other hormones such as parathyroid hormone (PTH) and vitamin D. However, calcitonin is more important in regulating calcium levels in infants, where it may play a more significant role in bone growth and development.

Calcitonin also has pharmaceutical applications. Synthetic forms of calcitonin, such as calcitonin salmon, are used as medications to treat conditions such as osteoporosis, where they can help to increase bone density and reduce the risk of fractures. Additionally, calcitonin may be used to manage hypercalcemia (high blood calcium levels) in certain medical conditions.