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Calcitonin
Related Subjects: |Calcium Physiology |Calcitonin
🧪 Calcitonin (Salmon) can be used as a tumour marker for recurrence or metastasis in medullary carcinoma of the thyroid.
📖 About
- Always check the BNF for dosing and guidance.
- Used both as a diagnostic marker (thyroid cancer) and as a therapeutic agent (osteoporosis, Paget’s disease, hypercalcaemia).
⚙️ Mode of Action
- Provides analgesia in osteoporotic fractures.
- Inhibits osteoclast activity → reduces bone resorption.
- Increases renal excretion of calcium and phosphate.
🧠 Physiology
- Calcitonin = 32-amino acid peptide secreted by thyroid parafollicular (C) cells.
- Acts to lower serum calcium, opposing parathyroid hormone (PTH). ⚖️
- ↓ Osteoclast activity → ↓ bone resorption.
- ↓ Tubular reabsorption of calcium & phosphate → ↑ urinary loss.
📡 Calcitonin Receptor
- A G-protein coupled receptor (7-transmembrane type), mediating effects in bone and kidney.
🔔 Stimulus for Secretion
- Main trigger = raised serum calcium.
- Suppressed when calcium falls below normal. 📉
💊 Indications & Dosing (BNF)
- Hypercalcaemia of malignancy: SC/IM 100 units every 6–8 hrs (max 400 units/dose). Severe cases: IV infusion up to 10 units/kg over ≥6 hrs.
- Paget’s disease: SC/IM 100 units daily (max 3 months; 6 months in exceptional cases). Minimum regimen: 50 units 3×/week can still help.
- Acute bone loss (immobility): SC/IM 100 units daily initially, reduced to 50 units daily on mobilisation. Duration: 2–4 weeks.
⚠️ Interactions
- Check BNF for updated list of interactions.
🔎 Cautions
- Heart failure, allergy history.
- Risk of malignancy with long-term use → use lowest effective dose for shortest time.
🚫 Contraindications
- Hypocalcaemia (already low calcium levels).
💥 Side Effects
- GI: Abdominal pain, nausea, diarrhoea.
- Systemic: Flushing, fatigue, headache, dizziness.
- MSK: Joint and muscle pain.
- Long-term risk: Secondary malignancy. ⚠️
📚 References
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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