Characterization of normocalcemic primary hyperparathyroidism

The introduction of multichannel serum biochemistry testing in the early 1970s uncovered a large number of patients with primary hyperparathyroidism who were asymptomatic, turning an extremely rare and severe disease into a fairly common and benign condition ( 1 Wermers R.A. Khosla S. Atkinson E.J. Hodgson S.F. O’Fallon W.M. Melton III, L.J. The rise and fall of primary hyperparathyroidism a population-based study in Rochester, Minnesota, 1965–1992. Ann Intern Med. 1997; 126: 433-440 Crossref PubMed Scopus (271) Google Scholar ). The diagnosis of primary hyperparathyroidism—whether symptomatic or not—still requires hypercalcemia along with an elevated intact parathyroid hormone (PTH) level ( 2 Bilezikian J.P. Silverberg S.J. Clinical spectrum of primary hyperparathyroidism. Rev Endocr Metab Disord. 2000; 1: 237-245 Crossref PubMed Scopus (66) Google Scholar ). Recently, endocrinologists have become aware of patients with normocalcemic primary hyperparathyroidism. This entity has not been characterized systematically, and it is not yet clear whether this is a “forme fruste” of the disease or a harbinger of the hypercalcemic type ( 3 Bilezikian J.P. Potts Jr, J.T. Asymptomatic primary hyperparathyroidism new issues and new questions- bridging the past with the future. J Bone Miner Res. 2002; 17: N57-N67 PubMed Google Scholar ). The purpose of the present study was to define the characteristics of patients with this diagnosis in one endocrine outpatient clinic during the last 5 years.