ATYPICAL PRIMARY HYPERPARATHYROIDISM DUE TO HYPOVITAMINOSIS D.

Vitamin D deficiency is nowadays very common in the general population and also in patients with primary hyperparathyroidism. Hypovitaminosis D may modify the clinical features and the severity of primary hyperparathyroidism. We present the case of a 75-year-old woman with a 10 year history of nephrolithiasis and severe osteoporosis, with multiple fragility fractures. Her bone and kidney status required a more thorough metabolic assessment. Despite minimal changes in serum calcium and phosphate levels, parathyroid hormone (PTH) level was markedly elevated. Ultrasound and specific Sesta-MIBI scintigraphy diagnosed and localized a left parathyroid adenoma. Vitamin D assessment showed levels in the range of hypovitaminosis. Vitamin D deficiency may mask hypercalcemia despite high serum PTH levels, and does not seem to diminish but on the contrary increases the risk of kidney lithiasis, as well as the deleterious effects of hyperparathyroidism on bone.