Calcitonin

Definition

Calcitonin is a hormone produced by the parafollicular cells (C cells) of the thyroid gland that plays a crucial role in regulating calcium levels in the blood. It primarily functions to lower blood calcium levels by inhibiting osteoclast activity, which decreases bone resorption, and promoting the deposition of calcium in bones. This hormone works alongside parathyroid hormone (PTH) to maintain calcium homeostasis in the body.

5 Must Know Facts For Your Next Test

1. Calcitonin secretion is stimulated by high blood calcium levels, helping to counteract hypercalcemia.
2. This hormone has a more significant role during childhood when bone growth is rapid, as it helps to promote the deposition of calcium into bones.
3. Calcitonin can be used therapeutically in conditions like osteoporosis and Paget's disease to help manage bone density.
4. While calcitonin primarily works to lower blood calcium levels, its overall impact is less critical than that of parathyroid hormone, which has a more dominant role in calcium regulation.
5. Calcitonin levels can vary based on factors such as age, sex, and certain medical conditions affecting thyroid function.

Review Questions

• How does calcitonin interact with parathyroid hormone in regulating calcium levels in the body?
  • Calcitonin and parathyroid hormone (PTH) have opposing effects on calcium regulation. While calcitonin lowers blood calcium levels by inhibiting osteoclasts and promoting bone formation, PTH increases blood calcium levels by stimulating osteoclast activity and enhancing renal reabsorption of calcium. The balance between these two hormones is essential for maintaining homeostasis of calcium in the body, ensuring that calcium levels remain within a narrow range necessary for various physiological functions.
• Discuss the role of calcitonin during childhood and how it contributes to skeletal health.
  • During childhood, calcitonin plays a vital role in skeletal health by promoting bone growth and mineralization. As children experience rapid growth, calcitonin helps deposit calcium into bones, ensuring adequate bone density and strength. This hormonal activity is particularly important during periods of high bone turnover when the risk of developing osteoporosis later in life can be influenced by early bone health. By regulating calcium levels effectively, calcitonin supports healthy skeletal development in growing individuals.
• Evaluate the therapeutic uses of calcitonin in managing certain medical conditions and its efficacy compared to other treatments.
  • Calcitonin is utilized therapeutically for conditions such as osteoporosis and Paget's disease due to its ability to inhibit bone resorption and promote bone density. While it can help reduce fracture risk in patients with osteoporosis, its efficacy is generally considered less potent compared to other treatments like bisphosphonates or hormone replacement therapy. Evaluating its use involves weighing benefits against potential side effects and considering patient-specific factors, such as existing medical conditions or response to other therapies, making it a part of a broader management strategy for bone health.

Related terms

parathyroid hormone (PTH): A hormone secreted by the parathyroid glands that increases blood calcium levels by stimulating osteoclast activity and enhancing calcium reabsorption in the kidneys.

osteoclasts: Cells responsible for bone resorption; they break down bone tissue and release calcium into the bloodstream, which is regulated by hormones like calcitonin and PTH.

thyroid gland: An endocrine gland located in the neck that produces hormones including calcitonin, thyroxine (T4), and triiodothyronine (T3), which regulate metabolism and calcium balance.