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January 2009

Severe Symptomatic Hypocalcemia in a Patient With RDEB Treated With Intravenous Zoledronic Acid

Arch Dermatol. 2009;145(1):95-96. doi:10.1001/archdermatol.2008.536

A 15-year-old boy with recessive dystrophic epidermolysis bullosa (RDEB) had severe osteopenia (lumbar spine bone mineral density, 0.348 g/cm2) (z score, −4.6; bone age–corrected z score, −3.6 [normal z score, greater than −2]) and compression fractures causing him to be bedridden. Prior to infusion of bisphosphonate, levels of serum ionized calcium (4.36 mg/dL; normal, 3.40-5.80 mg/dL), parathyroid hormone, phosphorous, and 25-hydroxyvitamin D were normal, as were results from renal function tests. He received intravenous elemental calcium (25 mg/kg) for hypocalcemia prophylaxis prior to his single intravenous bisphosphonate zoledronic acid infusion, 0.1 mg/kg (total dose, 4 mg, the recommended adult dose). This treatment was followed by administration of a repeated dose of intravenous elemental calcium (25 mg/kg), and then oral elemental calcium was prescribed (1500 mg, twice daily) along with cholecalciferol (6000 IU/d). Initial ionized calcium levels were normal for the next 24 hours. (To convert serum ionized calcium to millimoles per liter, multiply by 0.25.)

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