Denosumab-Induced Severe Hypocalcaemia in Chronic Kidney Disease

BACKGROUND: Hypocalcaemia is increasingly recognized as a complication of denosumab use in Chronic Kidney Disease (CKD) patients with osteoporosis. Despite Therapeutic Goods Administration (TGA) notifications in 2013, we have subsequently encountered several cases of denosumab-induced hypocalcaemia, raising concern about lack of widespread awareness among prescribing practitioners. AIMS: We reviewed the morbidity and healthcare intervention needs of CKD patients with hypocalcaemia attributed to denosumab. METHODS: A retrospective case series of CKD patients with clinically significant hypocalcaemia after exposure to denosumab, encountered at the tertiary care referral hospital from December 2013 to February 2017, was undertaken. RESULTS: Eight patients (52-85 years of age) with stage 4-5 CKD developed clinically significant hypocalcaemia (corrected calcium 1.45±0.21mmol/L) following denosumab therapy for osteoporosis. Seven of the eight patients required inpatient management with three patients requiring intravenous calcium replacement and cardiac monitoring in a high dependency unit. Our study also identified additional factors that could potentially contribute to hypocalcaemia such as lack of calcium supplementation, use of noncalcium based phosphate binders, absence of or use of lower doses of calcitriol supplementation, low vitamin D levels, concomitant treatment with loop diuretics, history of parathyroidectomy, or presence of acute medical illness. CONCLUSION: Multiple cases of severe hypocalcaemia in CKD patients following denosumab exposure were encountered after TGA warnings, resulting in considerable morbidity and intensive healthcare interventions in CKD patients. We advocate greater awareness amongst the medical profession, careful consideration before using denosumab in CKD patients, and close follow-up after administration to prevent morbidity.