Hypercalcemia associated with Wegener's granulomatosis and hyperparathyroidism: etiology and management.

We report a case of hypercalcemia in a patient with coexisting hyperparathyroidism and Wegener's granulomatosis. Parathyroidectomy with removal of an adenoma resulted in a low parathyroid hormone level but high calcitriol levels and hypercalcemia persisted. In various granulomatous diseases, hypercalcemia has been shown to be the result of overproduction of 1,25-dihydroxy-vitamin D by disease-activated macrophages. Chloroquine has been demonstrated to effectively reduce the extrarenal synthesis of 1,25-dihydroxyvitamin D and serum calcium concentration in hypercalcemic patients with sarcoidosis. Hypothesizing that a similar mechanism would explain hypercalcemia in Wegener's granulomatosis as well, a therapeutic trial of chloroquine was initiated. The patient responded to chloroquine 500 mg twice daily with significant decreases in serum 1,25-dihydroxyvitamin D and calcium levels. This report extends previous observations of hypercalcemia associated with other granulomatous diseases to Wegener's granulomatosis and demonstrates an effective reduction of serum calcitriol and calcium levels in response to chloroquine therapy.