Overview
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In plain language
Calcitonin is a natural hormone made in the thyroid gland. It is a chain of 32 amino acids that helps lower calcium levels in the blood by slowing the cells that break down bone.
A version taken from salmon is used as a medicine, because it is much stronger in people than human calcitonin. It has been used for Paget's disease of bone, very high blood calcium and, in the past more often, osteoporosis. Doctors also measure calcitonin as a marker for a rare thyroid cancer.
For students
Calcitonin is a 32-residue peptide (about 3,432 Da for the human form) secreted by parafollicular C cells of the thyroid in response to high calcium. It has a Cys1–Cys7 disulfide ring and a C-terminal prolinamide.
It binds the calcitonin receptor, a class B GPCR, on osteoclasts, rapidly inhibiting bone resorption. Salmon calcitonin differs from human calcitonin at 16 positions and is more potent and longer-acting in people, which is why it is the therapeutic form (injection and nasal spray).
For researchers and instructors
Physiology. Despite clear pharmacological effects, calcitonin's physiological role in adult human calcium balance appears minor: people after thyroidectomy or with medullary thyroid carcinoma have normal calcium.
Clinical use. Injection for Paget's disease and hypercalcemia (effect wanes with escape/tachyphylaxis); nasal spray for postmenopausal osteoporosis, now largely superseded by bisphosphonates and other agents.
Safety. A 2013 FDA review of pooled trials found a small increased risk of malignancy with long-term use; benefits are judged against this risk.
Biomarker. Serum calcitonin is a tumor marker for medullary thyroid carcinoma. Discovered by Copp in 1962.
Molecular identity
- Amino acids
- 32
- Molecular weight
- ~3,431.9 Da
- Formula
- C₁₄₅H₂₄₀N₄₄O₄₈S₂
- Sequence
- CSNLSTCVLGKLSQELHKLQTYPRTNTGSGTP-NH₂ (salmon; Cys1–Cys7 disulfide)
Sequence map
Hydropathy
Kyte–Doolittle score per residue. Positive values are water-repelling.
Origin and history
Calcitonin was discovered in 1962 by Harold Copp at the University of British Columbia in Vancouver, who found a hormone that quickly lowers blood calcium. He first thought it came from the parathyroid glands, but by 1964 it was traced to the thyroid’s C cells.
Salmon calcitonin turned out to be far more potent in humans than our own and became the drug form, including a nasal spray approved for osteoporosis in 1995. Its use has since declined in favor of other treatments.
Key people
- D. Harold CoppUniversity of British Columbia
Timeline
- 1962
Calcitonin discovered
- 1964
Traced to the thyroid
- 1995
Nasal salmon calcitonin approved for osteoporosis
See every peptide on one history timeline.
Human evidence
Approved for Paget’s disease of bone and high blood calcium; its use for osteoporosis has declined.
Registration and enrollment are not proof of benefit; check study results directly.
Explore original publications and distinguish preclinical findings from controlled human evidence.
Safety and regulatory status
See every compound on the regulatory tracker.
FDA-approved (injection and nasal spray). A 2013 FDA review noted a possible small increase in cancer risk with long-term use.
This profile is educational and does not provide treatment, dosing or sourcing guidance.
Sources
- PubMed literature search: Calcitonin
- PubChem compound search: Calcitonin
- DailyMed (FDA label search): Calcitonin
- PubMed: Copp 1962 calcitonin
- ClinicalTrials.gov search: Calcitonin
Hernandez Gener, E. (2026, November 7). Calcitonin: molecular data, research history and evidence. VALREXA Biosciences. https://valrexa.com/peptides/calcitonin.html
APA style · Last reviewed November 7, 2026 · Our editorial standardsLast reviewed November 7, 2026. Trial and regulatory status can change; confirm in the linked registries. This profile is educational and is not medical advice, a treatment recommendation, or dosing or sourcing guidance. Report an error · Corrections policy