Intraoperative monitoring of intact parathyroid hormone during surgery for primary hyperparathyroidism

The aim of the present study was to evaluate a new immunometric assay for intraoperative parathyroid hormone monitoring. The test was applied in 70 patients who underwent surgery for primary hyperthyroidism (pHPT) between 6/1999 and 6/2001. Among these patients, 61 showed a solitary adenoma, eight a hyperplasia and one a double adenoma. Intraoperative iPTH samples were taken at the beginning of the operation and 5, 10 and 15 min after removal of the parathyroid gland. Criterion for a successful operation were a decrease of iPTH levels of more than 50 % within 5 min and of more than 60 % within 15 min after parathyroidectomy. Following the removal of a solitary adenoma, iPTH levels decreased by 63 % (+/- 13 %) after 5 min and by 76 % (+/- 10 %) after 15 min respectively. In case of hyperplasia, a significant decrease of iPTH levels was not observed until a subtotal parathyroidectomy had been carried out. In the present study there were 2 false negative and one false positive results corresponding with a sensitivity of 97 % and a specificity of 89 % for prediction of a solitary adenoma. In our opinion, intraoperative iPTH monitoring using this new assay allows the safe distinction between adenoma and multiglandular disease. It represents a valuable adjunct to surgical skill as it permits minimally invasive operations for solitary adenomas, and in case of recurrent surgery helps to detect the region of interest by selective venous sampling for parathyroid hormone.