Normocalcemic primary hyperparathyroidism

Over the past two decades, normocalcemic primary hyperparathyroidism (NPHPT) has emerged as a new subset of primary hyperparathyroidism which, after exclusion of secondary hyperparathyroidism, is characterized by consistent normocalcemia with elevated parathyroid hormone levels. Population-based epidemiologic data lack reproducibility and generalizability. NPHPT has primarily been diagnosed in subjects referred for evaluation of symptoms related to this metabolic disease. However, an asymptomatic phase of the disease does appear to occur in the general population, suggesting that primary hyperparathyroidism is a spectrum that encompasses both normocalcemia and hypercalcemia that occurs in parallel with, but is not necessarily linked to, silent and symptomatic disease. In the current absence of good evidence, management recommendations for asymptomatic PHPT cannot be applied to patients with NPHPT.