[Evaluation of different intraoperative iPTH assay criteria in monitoring of minimally invasive parathyroidectomy for primary hyperparathyroidism].

INTRODUCTION

Intraoperative iPTH assay (IOPTH) is often used during minimally invasive parathyroidectomy (MIP) to predict operative success. The aim of this study was to evaluate diagnostic accuracy of IOPTH during MIP with respect to few prognostic criteria most commonly used.

METHODS

A retrospective study of 455 patients with sporadic primary hyperparathyroidism undergoing MIP with IOPTH at our institution between 2003 and 2012 was undertaken. Diagnostic accuracy of few prognostic criteria most commonly used was done including Halle, Miami, Rome and Vienna criteria. Results of IOPTH were compared to outcomes of MIP in 6-months follow-up after surgery (serum calcium and iPTH levels). Both ROC (Receiver Operating Characteristics) curve and error matrix analysis were used for accuracy assessment of IOPTH prognostic criteria. Based on this method the following accuracy parameters were calculated for each IOPTH criterion separately: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy.

RESULTS

The following diagnostic accuracy parameters of IOPTH were found for each of the tested criteria (sensitivity, specificity, PPV, NPV, accuracy), respectively: for Halle criterion 63.2%, 100.0%, 100.0%, 12.6%, 65.1%; for Miami criterion 97.7%, 96.4%, 99.8%, 73.0%, 97.6%; for Rome criterion 84.4%, 100.0%, 100.0%, 27.2%, 85.3%; for Vienna criterion 93.7%, 92.3%, 99.5%, 47.1%, 93.6%.

CONCLUSIONS

Miami criterion of IOPTH is the most accurate in prognostication of postoperative serum calcium levels after MIP. Use of other criteria may involve a higher risk of false negative results and unnecessary conversion to more extensive neck dissection in search for non-existent hyperfunctioning parathyroid tissue.