Applicability of ashortened interpretation model for intraoperative parathyroid hormone monitoring in patients with primary hyperparathyroidism in an endemic goiter region

BackgroundIn primary hyperparathyroidism (pHPT), quick intraoperative parathyroid hormone monitoring (IOPTH) is performed to predict complete excision of hyperfunctioning tissue and therefore cure. In recent years, efforts have been made to make this prediction more accurate and to shorten the duration of the test, respectively, and therefore reduce waiting and total operating time. The aim of this study was to evaluate the practicability and safety of atime-reduced criterion (decline35% after 5min) in alarge cohort of patients.MethodsIn an 11-year period, all patients operated for pHPT were analyzed. After preoperative localization studies, hyperfunctioning parathyroid tissue was removed and IOPTH monitoring was performed. Intraoperatively, adecline of 50% from baseline 10min after excision of the gland predicted cure. The performance of an interpretation model, using an earlier PTH level was analyzed retrospectively (decline35% from baseline 5min after excision). Differences in sensitivity, specificity, positive/negative predictive value and accuracy were calculated.ResultsAccording to the inclusion criteria, 1018 patients were analyzed. IOPTH predicted cure in 854 patients (83.9%) 10min after gland excision with afalse positive decline in 13patients (1.5%). Applying the modified criterion (35% decline within 5min), 814 patients (80%) showed an appropriate decline (false positive in 18 [2.2%]). Overall, multiple gland disease would have been missed in 7patients. McNemar's test showed asignificantly lower sensitivity, specificity and accuracy applying the 35% criterion.ConclusionsIn an endemic goiter region, acriterion, demanding a35% decline 5min after excision can not be recommended for IOPTH monitoring in patients with pHPT.