Abstract

Primary hyperparathyroidism is the third most common endocrine disorder and the most common cause of hypercalcemia in the outpatient setting. After the introduction of automated serum calcium measurements in the 1970s, its prevalence increased significantly. In addition, the clinical phenotype had shifted from a symptomatic disorder to a less symptomatic or even asymptomatic state. This clinical profile has been called asymptomatic primary hyperparathyroidism. A newer presentation of primary hyperparathyroidism has been described over the past decade, in which parathyroid hormone is elevated but total and ionized serum calcium concentrations are consistently normal, in the absence of secondary causes for elevated parathyroid hormone concentration. This new condition has been called normocalcemic primary hyperparathyroidism. This review presents the current data in relation to this newly described type of primary hyperparathyroidism.

Key words: Normocalcemic hyperparathyroidism, primary hyperparathyroidism, parathyroid hormone, total serum calcium, ionized serum calcium, bone disease