Hypercalcemia during Long-Term Treatment with 1,25-Dihydroxyvitamin D₃ in Hypoparathyroidism

To the Editor: We previously reported on two patients with pseudohypoparathyroidism who were receiving long-term maintenance treatment with 1,25-dihydroxyvitamin D₃ (l,25(OH)₂D₃), and who had spontaneous hypercalcemia and increases in serum l,25(OH)₂D.¹ These abnormalities were corrected by stopping the drug, and recurrences were prevented by subsequent reduction of the dosage. We have recently observed a similar sequence of events in a patient with hypoparathyroidism. A 75-year-old woman with hypercalcemia, impaired renal function, and a normal level of serum immunoreactive parathyroid hormone (PTH), had noncaseating granulomas in lymph nodes obtained during mediastinal exploration and excision. No extract is available for articles shorter than 400 words.