Intraoperative parathyroid hormone assay and parathyroid reoperations

Background. The purpose of this study was to determine whether intraoperative parathyroid hormone (IOPTH) assay improved results of reaperations. Methods. One hundred two patients with persistent/recurrent sporadic primary hyperparathyroidism underwent 108 reoperations (1996-2002). IOPTH was not used (n = 58) from 1996-1998 (group 1). IOPTH was used (n = 50) from 1999-2002 (group 2). Sensitivity and positive predictive value of IOPTH and its influence on surgical strategy were analyzed. A 50% decrease occurring 10 minutes after removal of parathyroid tumor was used to determine if all abnormal tissue had been removed. Results. Groups 1 (58 patients) and 2 (50 patients) were comparable except for duration of follow-up. The cure rate was 84% (group 1, 87%; group 2, 82%, P = 0.7). Hypocalcemia developed in 20 Patients (permanent in 2 patients). There was 1 permanent vocal cord paralysis and 1 patient died of toxic shock syndrome. IOPTH successfully predicted cure in 44 of 49 patients (sensitivity, 90% the positive predictive value was 90%. Values for parathyroid hormone level and the ratio parathyroid hormone/calcium at day 1 were at least as accurate as IOPTH in predicting cure. IOPTH was helpful in 1 patient but misleading in 4 patients. It failed to modify intraoperative strategy in most other patients. Conclusions. IOPTH testing was relatively reliable in patients with persistent or recurrent sporadic primary hyperparathyroidism, but the test unfortunately failed to improve the overall success rate at reoperation.