We report a case of parathyroid hormone (PTH)-mediated symptomatic persistent hypercalcemia in an end stage renal disease (ESRD) patient on maintenance hemodialysis. Our case is unusual for rapid development of functionally active giant parathyroid adenoma in a dialysis dependent patient, and challenges in managing hypercalcemia refractory to standard medical therapy and hemodialysis.

A 67-year-old woman with background history of ESRD on hemodialysis since 2019, stable monoclonal gammopathy of undetermined significance presented with two weeks of gradual functional decline and symptoms of hypercalcemia - lethargy, confusion and altered mental state, unsteady gait, poor oral intake, abdominal bloating and constipation. Corrected serum calcium was markedly elevated at 3.62mmol/dL, with raised intact PTH at 117pmol/L. Ultrasound showed a well-defined 29 x 22 x 12mm hyperechoic nodule posterior to the right thyroid lower pole, consistent with a parathyroid adenoma which was congruent with a region increased sestamibi tracer uptake with delayed tracer washout on parathyroid scintigraphy.

Despite treatment of hypercalcemia with repeated hemodialysis with low calcium dialysate, maximal doses of cinacalcet, followed by calcitonin and anti-resorptives, her calcium levels remained persistently high above 3.2mmol/dL. She underwent definitive treatment with total parathyroidectomy and deltoid implantation with expected response in iPTH levels, however remained persistently hypercalcemic in the immediate post-operatively period.

Persistent hypercalcemia in an ESRD dialysis patient deserves thorough evaluation for etiology despite institution of treatment for presumptive tertiary hyperparathyroidism. We also take the opportunity to share our experience in managing refractory hypercalcemia prior to and post-operatively for this patient with a giant parathyroid adenoma.