PARATHYROID TISSUE IN NORMOCALCEMIC AND HYPERCALCEMIC PRIMARY HYPERPARATHYROIDISM RECRUITED BY HEALTH SCREENING

Parathyroid tissue from 57 women (mean age 65.5 years) with sporadic p rimary hyperparathyroidism (HPT) was analyzed mainly to clarify its ch aracteristics versus tissue from those with normocalcemia. Patients we re recruited by population-based health screening of menopausal women. Analysis of three or four total serum calcium values showed normocalc emia in 16 patients (mean 2.53 mmol/L); 20 and 21 of the women were co nsistently (mean 2.82 mmol/L) or intermittently (mean 2.59 mmol/L) hyp ercalcemic, respectively. Parathyroid operation demonstrated a single adenoma in 81% of the individuals, and these lesions were most prevale nt and commonly dominated by oxyphil parathyroid cells in the persiste ntly hypercalcemic patients. Chief cell hyperplasia (two or three abno rmal glands) of the nodular type was found more often in the normocalc emic patients. Total glandular weight was the smallest (mean 270 mg) a mong the normocalcemic women and contributed to delicate decisions wit h regard to the extent of resection. Immunostaining of cryosections wi th a monoclonal antibody recognizing a putative Ca2+ sensor demonstrat ed variably heterogeneous down-regulation of the recognized glycoprote in in the pathologic parathyroid glands from all the individuals. Dose -response relations for PTH release and the cytoplasmic Ca2+ concentra tion ([Ca2+](i)) were determined in Ca2+ 0.5-3.0 mmol/L by examining d ispersed cells with radioimmunoassay and microfluorometry after fura-2 loading, respectively. ED(50) for PTH release and [Ca2+](i) and the [ Ca2+](i) concentrations at Ca2+ 3.0 mmol/L were the least deranged in cells from pathologic glands of the normocalcemic patients. The findin gs substantiate that the abnormal parathyroid tissue of normocalcemic HPT principally is characterized by the same, albeit less extensive, m orphologic and functional derangements, which consistently have been d emonstrated in patients with HPT accompanied by hypercalcemia and dete cted clinically.