As part of management of lytic bone lesions in patients with multiple myeloma, patients are given either Zoledronic Acid or Pamidronate Disodium at our Haematology Medical Day Unit. This project was started after an incident of a bisphosphonate induced hypocalcaemia secondary to signifi- cantly low 25-hydroxyvitamin D (25-OHD) in early September 2015. A 67 year old female with newly diagnosed multiple myeloma received Zoledronic Acid infusion. A few days later on her routine follow-up, she was found to have a low adjusted calcium of 1.74mmol/L. Of note, her adjusted calcium was normal before the infusion.
Further tests revealed significantly low (25-OHD) of less than 20nmol/L, phosphate of 0.5mmol/L, parathyroid hormone (PTH) of 39.6 pmol/ L. She had no signs of hypocalcaemia. After repeat blood test, she was treated urgently with 10% of calcium gluconate infusion and was discharged home with alfacalcidol and calcium carbonate tablets with a follow-up appointment. Although this patient did not come to any significant harm, if this was left untreated, she could have potentially suffered with symptomatic hypocalcaemia and life threatening cardiac arrhythmias.
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