Optimal use of intraoperative PTH levels in parathyroidectomy

Objectives/Hypothesis: Localization and the intraoperative parathyroid hormone assay (IOPTH) have facilitated minimally invasive parathyroidectomy. The precise algorithm governing use of IOPTH has been debated. Numerous authors advocate acquisition of a so-called pre-excision (P-E) baseline level (obtained after dissection of the adenoma, but prior to excision) in addition to a preincision baseline, to guard against spurious elevation in the baseline that might confuse interpretation of postexcision levels. We sought to clarify the optimal timing of PTH level determination. Study Design: Consecutive single-surgeon case series with planned data collection from patients undergoing parathyroid surgery at a university hospital. Methods: Demographic data and intraoperative laboratory and surgical findings from patients undergoing parathyroidectomy were prospectively gathered and analyzed. Attention was paid to the value of P-E and 5-minute postexcision levels and their impact on intraoperative decision-making. Results: One hundred twelve patients underwent parathyroidectomy. Thirty were for secondary or tertiary hyperparathyroidism and were excluded. Seventy-nine (96.3%) of the 82 patients with primary hyperparathyroidism were rendered eucalcemic. In no case did the P-E value change what was otherwise destined to be a successful result. In 65.3% of cases, operative time was conserved as the procedure was correctly stopped after the 5-minute level, without the need to wait until the 10-minute postexcision level was reported. Conclusions: Pre-excision baseline IOPTH levels, although logical in their original proposal, appear to play little role in determining the completeness of an exploration. A 5-minute postexcision level adds value in nearly two thirds of cases by allowing earlier termination of the operation.