Hypercalcaemia (calcium level >2.63 mmol/L) is a common metabolic condition. In spite of its diverse aetiologies, primary hyperparathyroidism and malignancy account for more than 90% of cases, parathyroid adenoma alone contributing to 8085% of parathyroid related cases. We describe a case of resistant hypercalcemia in a 75-year-old Afro- Caribbean gentleman.
He presented with a 2-month history of constipation, loss of appetite & gradual weight loss. He suffered from diabetes and hypertension but was not on a diuretic. He was mildly dehydrated but general and systemic examination was entirely unremarkable.
His admission calcium was 4.16 mmo/l. PTH level was raised on 2 occasions (1042 pg/ml and 1043 pg/ml), but he had normal renal & liver function, ACE level, thyroid function, testosterone, PSA, Prolactin, IGF-1 and GH level. Vasculitic, auto-immune and myeloma screen were normal. Urinary metanephrines and CXR was normal. His bone scan was normal with no evidence of metastasis. CT abdomen was normal apart from a slightly bulky left adrenal gland.
Ultrasound thyroid demonstrated a large (24×17 mm) nodule in the posterior right lobe but parathyroid MIBI scan showed no evidence of parathyroid adenoma.
He was treated with IV fluids and and Pamidronate but his calcium levels persisted above 3.2 mmol/L. He was then treated with Salmon Calcitonin on four occasions but his calcium levels persisted above 4.11 mmol/L. We suspected parathyroid carcinoma with such resistant hypercalcemia, raised PTH and a negative MIBI scan. However, following neck exploration and a parathyroidectomy, histology was suggestive of a parathyroid adenoma. Post-operatively, his calcium levels were normal.
Although resistant hypercalcaemia with grossly raised PTH in the elderly raises the suspicion of parathyroid carcinoma or an underlying malignancy, primary hyperparathyroidism should still be considered as it is relatively more common than other aetiologies. Most surgical centres nowadays do not rely on pre-operative localisation of parathyroid adenomas, which may sometimes be very difficult. Surgical exploration of the neck should be undertaken in all cases of resistant hypercalcaemia, especially when all localising investigations have proven futile and the cause remains uncertain.