RT Journal Article SR Electronic T1 Denosumab-induced severe hypocalcaemia in a patient with vitamin D deficiency JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e234508 DO 10.1136/bcr-2020-234508 VO 13 IS 8 A1 Natasha Daga A1 Flavian Joseph YR 2020 UL http://casereports.bmj.com/content/13/8/e234508.abstract AB Postmenopausal women are at increased risk of osteoporosis. Osteoporotic fractures carry an increased risk of morbidity and mortality. Denosumab is a monoclonal antibody widely used for the treatment of osteoporosis by inhibiting osteoclast-induced bone resorption. Hypocalcaemia is a known side-effect of denosumab treatment. The majority of such cases have been described in patients with underlying metastatic cancer or chronic kidney disease. We present a patient who developed severe hypocalcaemia after administration of denosumab in the context of severe vitamin D deficiency and a normal kidney function. The management was further complicated by hypophosphatemia. Following replacement of vitamin D, the patient’s calcium and phosphate levels stabilised. The patient required intensive care monitoring for replacement of electrolytes. This case report emphasises the importance of screening and ongoing monitoring of risk factors for iatrogenic hypocalcaemia with denosumab treatment.