The aim of the study is to compare the results of a parathyroid hormone (PTH)suppression test using a single oral tablet of cinacalcet in two groups of subjects: 1- a group of healthy adults in whom the results of the test with cinacalcet will be compared with those of the standardized PTH suppression test with intravenous calcium loading; 2- a group of patients with proven primary hyperparathyroidism in whom the results of the test with cinacalcet will be compared with those obtained during the same test, in healthy controls.