[Intraoperative monitoring of intact parathyroid hormone (iPTH) in surgery of primary hyperparathyroidism with a new rapid test].

OBJECTIVES Intraoperative differentiation between adenoma and hyperplasia during surgery for primary hyperparathyroidism (pHPT) is sometimes difficult, but essential for good results. The aim of our study was to evaluate a new highly sensitive electrochemiluminescence immunoassay (ECLIA) for intraoperative monitoring of intact parathyroid hormone (iPTH) following parathyroidectomy as an adjunct for identification of solitary adenoma in patients with pHPT. METHODS Thirty consecutive patients with pHPT (2 with recurrent pHPT) were examined following a standardized protocol: Immediately before and 5, 10 and 15 min following parathyroidectomy of the enlarged gland, iPTH was measured with a new ECLIA (Roche-Diagnostics, Mannheim, Germany). The results were available within 15-20 min. Besides 20 conventional bilateral neck explorations, parathyroidectomy was carried out in a minimally invasive video-assisted technique (MI-VAP) in 10 patients. RESULTS Among the 30 patients we found 24 with solitary adenoma (80%), 5 with hyperplasia (17%) and one with a double adenoma (3%). Five minutes after removal of a solitary adenoma the level of iPTH had decreased by 65 (12)% [mean (+/- SD)], after 10 min by 76 (8)% and after 15 min by 81 (8)%. All patients with multiple gland disease could be clearly identified, as iPTH after 15 min did not fall below 50% of basal value. Only after removal of all hyperplastic glands did iPTH decrease to the normal range. Sensitivity and specificity for prediction of a solitary adenoma were 92% and 100% (decline of iPTH more than 50% from baseline value 5 min after parathyroidectomy). In one patient with recurrent pHPT intraoperative sampling from different sites in both internal jugular veins could predict the quadrant of the enlarged gland. Correlation (r) between the results of the quick and the conventional assay, which requires 24 h of incubation, was 0.955. All patients had normal or low calcium levels postoperatively. CONCLUSIONS (1) Intraoperative monitoring of iPTH with this new quick assay allows safe identification of patients with solitary adenoma during surgery for pHPT. (2) It represents a valuable adjunct to surgical skill not only in primary operations for pHPT but especially in cases of recurrent surgery for pHPT. (3) With this test available minimally invasive techniques for parathyroidectomy may be employed in cases of preoperatively localized adenoma (ultrasound, sesta-mibi scan), avoiding bilateral neck exploration with its higher potential for complications.