Endocrine Abstracts

Local and national guidelines for post- hip fracture bone protection in an elderly population, advise vitamin D replacement and IV bisphosphonate. We report the case of an 82 year old man who underwent left hemiarthroplasty after low-trauma neck of femur fracture. He received a loading dose of Vitamin D (150,000 units over six days) and followed by IV Zolendronic Acid 5 mg on day nine of admission. On admission the serum calcium was elevated (2.63 mmol/l), on repeat it was within range for intervention (2.59 mmol/l). He promptly developed PTH dependent hypercalcaemia (corrected Ca 3.19 mmol/l; PTH 31 pmol/l Phosphate 0.68 mmol/l) which was resistant to conventional management. Subsequent investigations showed; Vitamin D 25 nmol/l, eGFR >60 ml/min/1.73m², Calcium/Creatinine Ratio 0.0287. A DEXA scan showed osteopenia (T score Hip -1.6, T score spine 0.2). A Technetium-99m (sestimibi) scan reported tracer activity in the right mid pole of the thyroid likely parathyroid adenoma. Calcitriol (1, 25 OH Vit D) level was 66 pmol/l, 8 days after loading with Vitamin D. Hypercalcaemia was resistant to multiple lines of medical management, despite IV normal saline, IV furosemide, cinacalcet and prednisolone over nine days of, in addition to the recent IV Zolendronic acid given before this. Calcitonin stabilised the serum calcium for 48 hours. He had proximal myopathy, peripheral oedema, anorexia, nausea, vomiting and constipation. The serum calcium continued to rise to a maximum of 3.51 mmol/l, Denosumab 120 mg was given, a good response was achieved over 72 hours, the serum calcium normalised (2.5 mmol/l). Once normocalcaemic, he symptomatically improved before discharging. Controversy exists about the role of Vitamin D replacement in primary hyperparathyroidism. This case highlights the potential impact of high-dose Vitamin D exposure and the difficulty in correcting consequent hypercalcaemia in patients with primary hyperparathyroidism.