Calcitonin Dosing for Hypercalcemia
For acute hypercalcemia requiring rapid calcium reduction, administer calcitonin-salmon 4 IU/kg subcutaneously or intramuscularly every 12 hours (or 8 IU/kg divided into 4 doses daily for severe cases), used only as bridge therapy while awaiting bisphosphonate effect, as tachyphylaxis develops within 48-72 hours. 1, 2
Dosing Regimens
Standard Dosing
- Calcitonin-salmon 4 IU/kg subcutaneously or intramuscularly every 12 hours is the typical acute dosing regimen 1, 3, 4
- For severe hypercalcemia, 8 IU/kg/day divided into 4 doses (2 IU/kg every 6 hours) provides more aggressive calcium reduction 3
- Alternative dosing: 100 IU subcutaneously or intramuscularly every other day for less urgent situations 5, 2
Route of Administration
- Subcutaneous or intramuscular injection is preferred for acute hypercalcemia management 2, 3, 4
- Nasal spray formulation (200 IU daily) exists but is indicated only for osteoporosis treatment, not acute hypercalcemia 5, 2
- Rectal suppository formulation has been used successfully in research settings without flushing or nausea 6
Clinical Context and Combination Therapy
Role in Treatment Algorithm
Calcitonin should never be used as monotherapy for hypercalcemia but rather as part of a comprehensive approach: 1, 2
- IV normal saline hydration (targeting urine output 100-150 mL/hour) is the foundational treatment 1, 2
- Zoledronic acid 4 mg IV (infused over ≥15 minutes) provides definitive sustained calcium control 1, 2
- Calcitonin bridges the gap during the 2-4 day delay before bisphosphonates take effect 1, 2, 4
Onset and Duration of Action
- Calcitonin works within 2-4 hours, making it the fastest-acting hypocalcemic agent available 1, 7
- Peak effect occurs at 24-48 hours after initiation 7
- Tachyphylaxis (escape phenomenon) develops within 48-72 hours, limiting utility to 4-7 days maximum 1, 7
Special Populations and Considerations
Pediatric Dosing
- Same weight-based dosing applies: 4-8 IU/kg/day divided into 2-4 doses 3, 4
- Pediatric case reports demonstrate successful use of 8 IU/kg/day in 4 divided doses combined with pamidronate 1 mg/kg for malignancy-related hypercalcemia 3
Renal Impairment
- Calcitonin is safe in patients with renal insufficiency or oliguria, unlike bisphosphonates which require dose adjustment 2, 7
- This makes calcitonin particularly valuable when zoledronic acid must be withheld due to creatinine clearance <35 mL/min 2
Cardiac Insufficiency
- Safe in patients with congestive heart failure who cannot tolerate aggressive IV hydration 7
Critical Pitfalls to Avoid
Do Not Use as Monotherapy
- Never rely on calcitonin alone for definitive hypercalcemia management—always combine with bisphosphonates unless contraindicated 1, 2
- The calcium-lowering effect is modest (typically 1-2 mg/dL reduction) and temporary 7
Discontinue After 72 Hours
- Stop calcitonin after 48-72 hours even if calcium remains elevated, as continued administration provides no additional benefit due to tachyphylaxis 1, 7
- If calcium remains elevated after 72 hours, consider alternative agents (denosumab, dialysis) rather than continuing ineffective calcitonin 2
Contraindications
- Allergy to calcitonin-salmon or synthetic calcitonin-salmon is an absolute contraindication 5
- Perform skin testing if hypersensitivity is suspected 1
Mechanism and Efficacy
Calcitonin lowers calcium through two mechanisms: 7
- Inhibits osteoclastic bone resorption
- Increases renal calcium excretion (calciuresis) by lowering the renal tubular reabsorption threshold 6
The calciuric effect is particularly valuable when the notional setting of renal tubular calcium reabsorption is elevated, as occurs in many malignancy-related hypercalcemia cases 6
Adjunctive Benefits
Analgesic Properties
- Calcitonin provides pain relief in patients with bone metastases, offering symptomatic benefit beyond calcium reduction 7