Bone & soft-tissue tumours (question 6): a free FRCS (Tr & Orth) Section 1 question

Severe hypercalcaemia of malignancy, here above 3.5 mmol/L with symptoms, is an emergency. Hypercalcaemia causes a nephrogenic diuresis and vomiting, so patients are profoundly volume depleted, which in turn reduces renal calcium excretion. The first step is vigorous rehydration with intravenous 0.9% sodium chloride, typically 4–6 litres over 24 hours with attention to cardiac and renal function. An intravenous bisphosphonate, usually zoledronic acid, follows once the patient is rehydrated: it is nephrotoxic in a dry patient and takes two to four days to act. Furosemide worsens dehydration and is used only for fluid overload. Calcitonin acts quickly but weakly and briefly. Steroids help in lymphoma and myeloma, not in breast cancer. Denosumab is used for refractory cases. Reference: Walsh J et al., Society for Endocrinology emergency guidance on acute hypercalcaemia, Endocr Connect 2016.