Case report of severe hypocalcemia with atypical symptoms after zoledronic acid in palliative care: a deprescribing pitfall

Symptomatic hypocalcemia is an uncommon metabolic disturbance in palliative care and may therefore be overlooked. While deprescribing is a key principle in this setting, routine discontinuation of calcium and vitamin D supplementation may be harmful in selected high-risk patients, particularly after recent antiresorptive therapy. A 74-year-old woman with hormone receptor-positive metastatic breast cancer, extensive bone metastases and chronic kidney disease, was admitted to a German palliative care unit. Four weeks prior, she had received zoledronic acid, and calcium and vitamin D supplementation were discontinued on admission. She subsequently developed persistent nausea, vomiting and bronchospasm without classical neuromuscular signs, which were initially attributed to other causes. At a corrected calcium nadir of 0.95 mmol/L intravenous calcium was started and symptoms resolved. Oral intake resumed and supplementation was restarted. She was discharged to hospice care and died nine months later. After recent antiresorptive therapy, especially in patients with additional risk factors such as renal impairment, hypocalcemia may present with atypical symptoms including nausea or bronchospasm. This case highlights a potential pitfall of deprescribing in palliative care and underscores the need for individualized decisions regarding calcium and vitamin D supplementation to prevent delayed diagnosis and avoidable symptom burden.