The regulation of parathyroid hormone (PTH) secretion by calcium was studied in normal
and abnormal parathyroid tissue from five patients with a parathyroid adenoma. Dispersed
cells were prepared from the adenoma and from a portion of a normal parathyroid gland and
were incubated for two hours with varying concentrations of calcium. PTH release as a
function of the concentration of calcium was determined by radioimmunoassay (C-terminal).
Cells from the normal glands showed a lower set-point for calcium (the concentration of …