Coexisting hyperthyroidism and primary hyperparathyroidism.

The simultaneous occurrence of hyperthyroidism and primary hyperparathyroidism is rare in the absence of previous neck irradiation. We report two cases from our institution. Hypercalcemia secondary to hyperthyroidism is common and may obfuscate the diagnosis of concomitant primary hyperparathyroidism. Therefore the continued presence of hypercalcemia in a patient with successfully treated hyperthyroidism should lead the physician to search for primary hyperparathyroidism. Treatment of these concomitant disease processes consists of combined thyroidectomy and parathyroidectomy.