Endocrine Abstracts

Background: There is limited data on the use of Denosumab for hypercalcaemia in patients with primary hyperparathyroidism (PHPT). We describe a case of severe hypercalcaemia in a critically ill patient with COVID, on a background of mild PHPT prior to hospital admission.

Case report: Seventy-seven-year-old gentleman with mild hypercalcaemia dating back to 2019, was referred to endocrinology with hypercalcaemia (adjusted calcium 4.02 mmol/l) and associated acute kidney injury (AKI). His PTH level at the time 31.8 pmol/l while his vitamin D level was 60 nmol/l. He remained hypercalcaemic despite intravenous fluids, Calcitonin, 2 doses of Pamidronate 60 mg, and Zoledronic acid 4 mg. Cinacalcet titrated to 360 mg daily was ineffective and poorly tolerated with a nadir adjusted calcium of 3.17 mmol/l. He then received 60 mg of Denosumab which brought his calcium level down to 2.80 mmol/l and subsequently within normal range, with resolution of the AKI and reversal of symptoms. A Sestamibi Parathyroid SPECT CT scan identified a solitary parathyroid adenoma and a renal ultrasound did not show any evidence of end organ damage. He remained hospitalised for 5 months due to COVID-related deconditioning and has required additional doses of Denosumab 4-6 monthly since discharge to maintain normocalcaemia, until optimised for a parathyroidectomy. Unlike prior cases in literature, we did not see hypocalcaemia in our patient, who has continued to require Denosumab.

Conclusion: This case illustrates that Denosumab is useful in the management of refractory hypercalcaemia associated with PHPT, particularly in those who are resistant to other therapies prior to surgery, or in patients in whom surgery is contraindicated or requires to be deferred. Denosumab could be considered when other modalities, like dialysis and emergency parathyroidectomy, cannot be easily undertaken due to comorbid conditions.