Refractory hypercalcemic crisis: A case of primary hyperparathyroidism with Gitelman syndrome

Primary hyperparathyroidism is characterized by hypercalcemia and hypophosphatemia caused by excessive parathyroid hormone secretion. Gitelman syndrome, a rare autosomal recessive salt-losing tubulopathy, presents with hypokalemia, hypomagnesemia, hypocalciuria, and secondary hyperaldosteronism. The coexistence of these conditions leads to an atypical clinical picture and may result in a refractory hypercalcemic crisis that responds poorly to standard therapies. We describe a case of refractory hypercalcemia accompanied by hypophosphatemia, elevated parathyroid hormone levels, hypokalemia, hypomagnesemia, and, notably, hypocalciuria that was inconsistent with the degree of hypercalcemia. The patient experienced recurrent hypercalcemic crises that required treatment with zoledronic acid and denosumab after conventional interventions failed. The diagnosis was ultimately confirmed through postoperative pathology and genetic testing. This case emphasizes that hypocalciuria in the setting of persistent hypercalcemia-especially when severe hypomagnesemia is present-should raise suspicion for underlying Gitelman syndrome. Early identification of this coexistence is essential, as optimal management requires surgical treatment of primary hyperparathyroidism followed by targeted correction of electrolyte abnormalities associated with Gitelman syndrome, ultimately improving clinical outcomes.