Using parathyroid hormone spikes during parathyroidectomy to guide intraoperative decision-making.

BACKGROUND: Intraoperative parathyroid hormone (IOPTH) level monitoring is a useful adjunct to parathyroidectomy for primary hyperparathyroidism (pHPT). Occasionally, increases ("spikes") in IOPTH levels from the preoperative baseline parathyroid hormone may occur, which may lead to longer operative times or more extensive neck exploration or both. The aim of this study was to determine if the extent of IOPTH level increase predicts single gland disease (SGD). METHODS: This is a retrospective review of a prospective parathyroid database of patients undergoing parathyroidectomy for sporadic pHPT from 1999-2013. Extent of parathyroid hormone spike was calculated by the difference in IOPTH level at the time of gland excision and baseline: group 1 had a decrease in IOPTH level, group 2 had IOPTH level increase one to three times above the baseline, and group 3 had IOPTH level increase greater than three times above the baseline. RESULTS: Of the 900 patients in the cohort, there were 634 patients (70%) in group 1, 234 (26%) in group 2, and 32 (4%) in group 3. SGD was identified in 88%, 78%, and 100% of patients in groups 1, 2, and 3, respectively. The median gland weight in group 3 (920 mg) was significantly larger than those in groups 1 and 2 (440 and 460 mg, respectively; P < 0.001). CONCLUSIONS: IOPTH level spikes occur in nearly one-third of patients undergoing parathyroidectomy for sporadic pHPT. Patients with extensive IOPTH level increase are more likely to have larger SGD, whereas patients with moderate IOPTH level increases have increased incidence of multigland disease. In patients with a significant increase in IOPTH levels and larger glands, no further surgical exploration may be indicated.