Endocrine Abstracts

Introduction: Parathyroidectomy is the only curative treatment for primary hyperparathyroidism (pHPT) and has been traditionally performed through bilateral neck exploration (BNE). However, with the use of intraoperative parathyroid hormone (IOPTH) assay along with preoperative localization exams, minimally invasive surgery can be performed with good surgical success rate.

Aim: To evaluate the usefulness of IOPTH assay in guiding adequate parathyroidectomy in patients with pHPT.

Materials and Methods: We retrospectively analysed the case records of patients who underwent parathyroidectomy for pHPT between 2003 and 2021 at our hospital. IOPTH monitoring was employed as an intraoperative tool to guide the surgical procedure. Blood samples were collected at pre-incision time and then 10–15 minutes after parathyroid gland excision. Successful surgery was defined as a drop of 50% or more in the IOPTH level, otherwise, BNE was performed. These results were compared to alternative strategies for IOPTH monitoring, including a 60% decline and reduction to parathormone (PTH) reference range values.

Results: A total of 99 patients were included. Post-excision PTH levels dropped >50% in 80 (80.8%) patients. 3 of 19 patients (15.8%) whose outcomes failed to reach curative criteria had confirmed multiglandular disease. Intraoperative PTH monitoring using our criteria showed a 91.7% sensitivity, 80% specificity and 89.9% accuracy. True positive among them were 77 (77.8%%), true negative 12 (12.1%), false positive 3 (3.0%) and false negative 7 (7.1%). If a normal PTH value was required as a criterion for cure, unnecessary BNE would have been performed in 32 patients (32.3%) and in 12 patients (12.1%) if a 60% decline was applied, compared with just 8 patients (8.1%) when using the previous criteria.

Conclusion: IOPTH in adjunct with other localizing studies was helpful for carrying out successful parathyroidectomy. The use of IOPTH had good sensibility in predicting cure for most of the patients with pHPT undergoing minimally invasive parathyroidectomy. The use of other criteria, such as 60% decline and normal PTH value 10–15 minutes after excision, was associated with higher rates of conversion to unnecessary BNE.