Secretion of intact PTH by dispersed human hyperparathyroid cells.

The rate of secretion of intact PTH by cells dispersed from adenomatous and hyperplastic human parathyroid tissue was measured using a two-site immunochemiluminometric assay specific for the intact peptide. Secretion rates were monitored following incubation in high and low-calcium media. The mean rate of secretion from hyperplastic cells was significantly greater (P less than 0.05) at low calcium and significantly more suppressible at high calcium (P less than 0.01) compared with adenomatous cells. These studies have demonstrated: (1) the calcium-dependent secretion of intact PTH, (2) that intact hormone release contributes to the non-suppressible component of secretion, and (3) differences in the secretory characteristics of adenomatous and hyperplastic parathyroid cells.