Recovery of parathyroid hormone secretion after parathyroid adenomectomy.

Using a sensitive two-site immunoradiometric assay which detects only intact human PTH-(1-84), we studied the kinetics of PTH secretion in 19 patients undergoing unilateral neck exploration and removal of a parathyroid adenoma. Preoperative serum PTH values averaged 116 ng/L (normal, 12-65 ng/L). In 8 patients in whom intraoperative sampling was performed, clearance of PTH-(1-84) was rapid, with virtual disappearance of PTH by 120 min after clamping the vascular pedicle to the adenoma. Analysis of the rate of disappearance of PTH-(1-84) indicated an exponential decay with a half-life of 21 min. Thirteen of 19 patients had serum PTH values less than 1 ng/L within 8 h after parathyroidectomy. Recovery of PTH secretion from the suppressed nonsurgically manipulated parathyroid tissue occurred during the nadir of postoperative hypocalcemia. Serum PTH was greater than 10 ng/L in 16 of 19 patients 30 h after removal of the PTH adenoma. Therefore, the functional recovery of atrophic parathyroid tissue is more rapid than that of other endocrine tissues studied to date.