An unusual cause of hypercalcemia from an endocrinologist's perspective

Calcium is an essential element that plays a crucial role in bone mineralization, neuromuscular transmission, and is involved in many cellular signaling processes. Its serum concentration (total albumin-corrected concentration) should range between 2.15 and 2.55 mmol/L and is strictly regulated by several mechanisms. Hypercalcemia is defined as an elevated level of serum calcium above 2.55 mmol/L. It has various causes, ranging from parathyroid gland dysfunction, most commonly in the form of primary hyperparathyroidism, through granulomatous diseases, to serious malignancies with skeletal invasion or paraneoplastic syndromes, such as ectopic production of parathyroid hormone (PTH) or parathyroid hormone-related protein. We report a case of a patient with incidentally detected severe hypercalcemia (3.69 mmol/L) and advanced chronic kidney disease with preserved diuresis. Through a comprehensive diagnostic evaluation, a granulomatous disease was identified as the underlying cause of the patient's metabolic disturbance. The aim of this report is to highlight the importance of a comprehensive approach to patients with hypercalcemia, where even less common causes may have adverse clinical consequences.

Keywords: hypercalcemia, parathyroid hormone, calcitriol, lymphadenopathy, renal insufficiency, granulomatous diseases.