Optimal Timing for PTH Assay in Parathyroidectomy

Objective 1) To assess the feasibility of a novel criterion for intraoperative parathyroid hormonal assay (iPTH) based on a single 10‐minute postexcision PTH level and using the workup PTH (wPTH) level as the baseline. 2) To compare the predictive value of this criterion with other recommendations for the timing of PTH acquisition. Methods A review of a single surgeon prospectively maintained parathyroidectomy database over a 2‐year period. Patients with primary hyperparathyroidism who underwent minimally invasive parathyroidectomy were included in the study. Results A total of 77 patients with a mean age of 54 ± 13.6 years met the inclusion criterion. The mean preoperative calcium was 11.12 ± 0.42 mg/dL. There was no correlation between the wPTH (mean = 138.33 ± 29.36 pg/mL) and the preincision (mean = 201 ± 90.7 pg/mL) and the preexcision (114 ± 82.5 pg/dL) PTH values. The sensitivity, specificity, PPV, NPV, and accuracy of using the wPTH level as the baseline and a normal 10‐minute postexcision level as a criterion was 98.6%, 66.6%, 98.6%, 66.6%, and 97.4%, which was comparable to the already defined criterion. Conclusion The pre‐excision and the pre‐incision values do not seem to change the overall accuracy of predicting surgical success if a single 10‐minute postexcision normal level is taken into consideration. A single normal 10‐minute postexcision iPTH assay is a feasible criterion that avoids multiple PTH samples and provides an acceptable predictive value for surgical success in minimally invasive parathyroidectomy.