Kalcytonin

Kalcytonin, also known as calcitonin, is a peptide hormone produced primarily by the parafollicular cells (C cells) of the thyroid gland in humans and other vertebrates. It plays a crucial role in calcium and phosphate metabolism by helping to regulate calcium levels in the blood.

The primary function of kalcytonin is to lower blood calcium concentrations when they are elevated. It achieves this by inhibiting the activity of osteoclasts, which are cells responsible for breaking down bone tissue and releasing calcium into the bloodstream. Additionally, it reduces calcium reabsorption in the kidneys, promoting its excretion in urine. These actions collectively help maintain calcium homeostasis, especially after meals or during periods of bone turnover.

Kalcytonin has clinical applications, particularly in the treatment of conditions related to abnormal bone metabolism. It is used to manage Paget's disease of bone, osteoporosis, and hypercalcemia, a condition characterized by excessively high calcium levels. Synthetic forms of calcitonin are administered via injections or nasal sprays.

In research, calcitonin serves as a biomarker for certain thyroid conditions, including medullary thyroid carcinoma, a type of cancer arising from C cells that overproduce the hormone. Its role in calcium regulation also makes it a focus of interest in understanding bone diseases and developing therapeutic interventions.

Overall, kalcytonin's precise regulatory functions in calcium and phosphate balance, along with its medical significance, underscore its importance in human physiology and clinical medicine.