Use and Misuse of IOPTH Levels During Parathyroidectomy

Objective The combined use of localization and intraoperative parathyroid hormone assay (IOPTH) has facilitated the performance of targeted or minimally invasive parathyroidectomy. The precise algorithm of the use of IOPTH has been debated. We sought to clarify the optimal sequence of testing. Methods After IRB approval was obtained, demographic data and intraoperative laboratory and surgical findings from patients undergoing parathyroidectomy were prospectively gathered and analyzed. Specific attention was paid to the value of pre-excision (P-E) values and the 5-minute postoperative (5-min) levels and their impact on intraoperative decision-making. In the first 49 consecutive patients, a P-E baseline value was sought; in all cases a 5-min value was obtained when possible. Results 112 patients underwent parathyroidectomy during the study period. 30 of these were for secondary or tertiary hyperparathyroidism and were excluded. 78 (95.1%) of the patients were eucalcemic. In 4 cases (4.9%), the incorporation of the pre-excision baseline value represented a false positive, and surgery was aborted prematurely. In no case did the P-E value change what was otherwise destined to be a successful result based on pre-incision value. In 47 cases (57.3%), operative time was conserved as the procedure was correctly stopped after the 5-min level. Conclusions Pre-excision baseline levels, while logical in their original proposal, appear to play virtually no role in determining the completeness of an exploration, and may in fact be misleading. A 5-minute postoperative level adds value in over one-half of cases by allowing earlier termination of the operation.