Calcitonin

Overview

Calcitonin is a 32-amino acid peptide hormone produced by parafollicular C-cells of the thyroid gland in response to elevated serum calcium. It acts through calcitonin receptors (CTR) on osteoclasts to inhibit bone resorption and on kidneys to promote calcium and phosphate excretion. Salmon calcitonin, which is approximately 40-50 times more potent than human calcitonin at the human receptor due to structural differences, is used clinically for Paget's disease, hypercalcemia, and osteoporosis (intranasal formulation). It also has significant analgesic properties, particularly for pain associated with vertebral fractures.

Mechanism of Action

Calcitonin binds the calcitonin receptor (CTR), a class B GPCR predominantly expressed on osteoclasts. CTR activation via Gs/cAMP/PKA causes rapid inhibition of osteoclastic bone resorption by: disrupting the osteoclast ruffled border (the acid-secreting membrane), reducing lysosomal enzyme release, and inducing osteoclast quiescence. CTR activation also occurs in renal tubules (promoting calcium/phosphate excretion) and CNS (mediating analgesic effects via descending pain modulation pathways). The analgesic mechanism involves central beta-endorphin release and serotonergic pathway activation.

Potential Benefits

• Osteoclast inhibition reducing bone resorption
• Paget's disease of bone treatment
• Hypercalcemia management
• Analgesic effect for vertebral fracture pain (intranasal formulation)
• Osteoporosis treatment (especially when other agents contraindicated)

Research Dosage Notes

The following reflects doses used in published research studies. This is not medical advice.

Paget's disease: 100 IU SC/IM daily. Osteoporosis analgesic (intranasal): 200 IU one nostril daily, alternating nostrils. Hypercalcemia: 4-8 IU/kg SC/IM q12h.

Amino Acid Sequence

Side Effects & Safety

• Nausea and flushing (SC/IM)
• Nasal irritation (intranasal)
• Hypocalcemia at high doses
• Rare: hypersensitivity reactions
• Long-term use associated with increased cancer risk (EMA review warning)

Synergistic Compounds

The following compounds have been studied alongside Calcitonin for potential complementary or synergistic effects:

Related Peptides

Learn More

References & Further Reading

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