calcitonin in severe hypercalcemia

Q: 48 years old male with known metastatic lung cancer is admitted to ICU with severe hypercalcemia of 16.3 mg/dL. The patient appears to be very vasculopath and the patient arrived from the ER with one peripheral IV, which also appears to be infiltrated now. Which route would be more efficacious to administer Calcitonin at this point? (select one)

A) subcutaneous

B) intra-nasal 

Answer: A

Intra-nasal Calcitonin is usually not effective. Even if a good IV line is available, the best route to administer calcitonin is either intramuscularly (IM) or subcutaneously (SC). The patient can be either calcitonin responsive or not. The initial dose is 4 units/kg. If the patient is responsive, the calcium level should decrease in the next 6 hours by 1 to 2 mg/dL. If the patient is responsive, the total further course is every 12 hours for the next 24 to 48 hours till the calcium level drops to a desirable level. 

If the patient appears unresponsive or partially responsive, the dose can be increased to 8 units/kg every 6 to 12 hours, for the next 24 to 48 hours. Simultaneous standard management of hypercalcemia with IV hydration should be pursued.

After 48 hours body develops tachyphylaxis due to receptor downregulation. The mechanism of action is dual i.e., via renal excretion of calcium and by decreasing bone resorption.

#electrolytes

References:

1. Chevallier B, Peyron R, Basuyau JP, et al. [Human calcitonin in neoplastic hypercalcemia. Results of a prospective randomized trial]. Presse Med 1988; 17:2375.

2. Kiriakopoulos A, Giannakis P, Menenakos E. Calcitonin: current concepts and differential diagnosis. Ther Adv Endocrinol Metab. 2022 May 21;13:20420188221099344. doi: 10.1177/20420188221099344. PMID: 35614985; PMCID: PMC9125613.

3. Walker MD, Shane E. Hypercalcemia: A Review. JAMA. 2022 Oct 25;328(16):1624-1636. doi: 10.1001/jama.2022.18331. PMID: 36282253.