Resolution of hypercalcemia in primary hyperparathyroidism with vitamin D replacement

Vitamin D deficiency is common in patients with primary hyperparathyroidism. We present a case of primary hyperparathyroidism with a positive parathyroid scan and history of nephrolithiasis. The patient had normal albumin and renal function but was vitamin D deficient. After treatment with vitamin D for 13 months, her parathyroid hormone values declined in parallel with the elevation in vitamin D. Although her total calcium normalized, her ionized calcium remained elevated throughout treatment. We believe vitamin D deficiency should be carefully monitored in primary hyperparathyroidism.