Refractory Shock Secondary to Denosumab-induced Severe Hypocalcaemia

Denosumab is one of the most commonly used antiresorptive drugs for osteoporosis treatment and the prevention of skeletal-related events in cancer patients. The purpose of this case report is to highlight potentially life-threatening severe hypocalcaemia as a side effect of denosumab complicated by refractory shock that failed to respond to medical management including intravenous calcium, vasopressors and inotropes in an elderly man with a history of prostatic cancer. LEARNING POINTS: Denosumab is a commonly used antiresorptive drugs for the treatment of osteoporosis and to prevent skeletal-related events in patients with cancer. A common side effect of denosumab is hypocalcaemia; conditions associated with a higher risk of hypocalcaemia include chronic kidney disease, pre-existing hypocalcaemia, and metastatic cancer. Severe hypocalcaemia may induce cardiovascular manifestations such as hypotension, bradycardia, impaired cardiac contractility, impaired vascular tone, and arrhythmias. Shock results from diminished vascular smooth muscle tone and tends to occur with rapid severe hypocalcaemia; it is usually refractory to fluid and pressor therapy until hypocalcaemia is corrected.