Calcitonin

Also known as: CALCA, P01258

**Mechanism of Action** Calcitonin, encoded by the *CALCA* gene (UniProt P01258), is a 32-amino-acid peptide hormone primarily secreted by parafollicular C-cells of the thyroid. It exerts its hypocalcemic and hypophosphatemic effects by binding to the calcitonin receptor (CTR), a G protein-coupled receptor expressed on osteoclasts and renal tubular cells. Activation of CTR inhibits osteoclast-mediated bone resorption, reducing the release of calcium and phosphate from bone matrix. In the kidneys, calcitonin enhances the urinary excretion of calcium, phosphate, and sodium, further contributing to lowered serum mineral levels. Its action is rapid (onset within minutes) but transient due to receptor desensitization and short plasma half-life (~10–15 minutes). **Key Research Findings** Experimental studies (PubMed ID: 29572) demonstrate that calcitonin administration induces a dose-dependent decrease in serum calcium in animal models, with maximal effect observed within 30–60 minutes. Research has also shown that calcitonin suppresses osteoclast activity via cAMP-dependent signaling and cytoskeletal rearrangement, leading to reduced bone turnover markers. In vitro, calcitonin inhibits osteoclast formation and survival, while in vivo, it attenuates hypercalcemia induced by parathyroid hormone or bone metastases. However, its clinical utility is limited by rapid tachyphylaxis and the development of neutralizing antibodies with prolonged use. **Clinical Relevance** Calcitonin is used experimentally for conditions such as Paget’s disease of bone, osteoporosis, and hypercalcemia of malignancy, though its role has been largely supplanted by bisphosphonates and denosumab due to superior efficacy and tolerability. Salmon calcitonin (a synthetic analog) is approved in some regions for postmenopausal osteoporosis and acute hypercalcemia, but its use is declining. Nasal and injectable formulations exist, but adverse effects (e.g., nausea, flushing) and the risk of malignancy (based on long-term animal studies) have limited its adoption. Current research focuses on calcitonin’s role in calcium homeostasis and potential applications in osteoarthritis and pain management. For research purposes only — not medical advice.

Key data

Mechanism of action

Calcitonin is a peptide hormone that causes a rapid but short-lived drop in the level of calcium and phosphate in blood by promoting the incorporation of those ions in the bones. Calcitonin function is mediated by the calcitonin receptor/CALCR and the CALCR-RAMP2 (AMYR2) receptor complex (PubMed:35324283)

Research & studies

Frequently asked questions

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