Does the final intraoperative PTH level really have to fall into the normal range to signify cure?

BACKGROUND

Intraoperative parathyroid hormone (IOPTH) helps shorten the duration of surgery and increase the likelihood of surgical cure. Although general consensus agrees that the IOPTH should fall by 50%, there is much debate as to whether the IOPTH needs to fall into the normal range.

METHODS

We retrospectively reviewed a prospective database of patients undergoing surgery for treatment of primary hyperparathyroidism. We included all patients with an IOPTH that fell by >50% by 10 or 15 min, but that did not fall into the normal range (parathyroid hormone remained ≥ 60 pg/ml). We excluded patients who had undergone prior neck surgery or had known multiple endocrine neoplasia 1 or 2.

RESULTS

A total of 1,231 patients underwent a parathyroidectomy, 155 of whom met the study's inclusion/exclusion criteria (12.6%). A total of 117 patients had an IOPTH fall by 50% by 10 min, and 38 patients' IOPTH fell by 50% by 15 min. Overall surgical cure rate was 98.7%. One patient from the 10-minute group and one patient from the 15-minute group had persistent disease on follow-up. One patient in the 15-minute group had recurrent disease. With a mean ± SEM 18.1 ± 2.1 months' follow-up, the recurrence rate in this cohort was 0.6%. The average calcium at last follow-up was 9.4 ± 0.0 mg/dl.

CONCLUSIONS

Allowing the IOPTH to fall by 50% by 15 min, regardless of whether the IOPTH falls into the normal range, results in a high success rate when performed by experienced surgeons. This helps reduce intraoperative time used waiting for additional parathyroid hormone levels and the risks associated with unnecessary bilateral neck exploration.