Denosumab (Prolia)

Hypocalcemia warning

Denosumab is a medication for treating osteoporosis. It is given as an injection (SC - subcutaneously) every 6 months. It inhibits osteoclasts that are the cells that break bone down. Some recommend checking a serum calcium before every injection because there is a warning about denosumab worsening hypocalcemia.  The warning is as follows:

Hypocalcemia: Denosumab may cause or exacerbate hypocalcemia; severe symptomatic cases (including fatalities) have been reported. An increased risk has been observed with increasing renal dysfunction, most commonly severe dysfunction (CrCl <30 mL/minute and/or on dialysis), and with inadequate/no calcium supplementation. Monitor calcium levels; correct preexisting hypocalcemia prior to therapy. Monitor levels more frequently when denosumab is administered with other drugs that can also lower calcium levels. Use caution in patients with a history of hypoparathyroidism, thyroid surgery, parathyroid surgery, malabsorption syndromes, excision of small intestine, severe renal impairment/dialysis, treatment with other calcium-lowering agents, or other conditions that would predispose the patient to hypocalcemia; monitor calcium, phosphorus, and magnesium closely during therapy (the manufacturer recommends monitoring within 14 days of injection [Prolia]. Concomitant use of calcimimetic medications may worsen hypocalcemia. Hypocalcemia lasting weeks to months (and requiring frequent monitoring) has been reported in postmarketing analyses. Administer calcium, vitamin D, and magnesium as necessary. Patients with severe renal impairment (CrCl <30 mL/minute) or those on dialysis may also develop marked elevations of serum parathyroid hormone (PTH). [1]

Rebound osteoporosis warning

There is a known problem when denosumab is stopped or missed patient can develop rapid worsening of bone density and spine fractures. What is the time frame that is of concern?

References

[1] Denosumab: Drug information. Lexicomp. 

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