Optimal use of intraoperative PTH levels in parathyroidectomy

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.

Consecutive single-surgeon case series with planned data collection from patients undergoing parathyroid surgery at a university hospital.

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.

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.

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.