> 80% Drop in Post-Excision Intraoperative Parathyroid Hormone Predicts High Rate of Cure in Both Classical and Normohormonal Primary Hyperparathyroidism

by Linda Kossoff •

CLINICAL QUESTION

In patients with normohormonal primary hyperparathyroidism (NHHPT), what percent reduction in post-excision intraoperative parathyroid hormone (IOPTH) from baseline would yield a rate of cure comparable to that in patients with classical primary hyperparathyroidism (PHPT)?

BOTTOM LINE

Patients with NHHPT undergoing parathyroidectomy can expect cure rates like those of patients with classical PHPT, with an 80% drop or more in IOPTH levels predicting a high likelihood of cure.

BACKGROUND: Primary hyperparat-hyroidism (HPT) classically presents with elevated parathyroid hormone (PTH) levels and hypercalcemia. Other recognized forms of primary HPT include normocalcemic HPT and normohormonal HPT. In the latter, normal-range PTH levels occur concurrently with hypercalcemia. Limited research has been conducted on the expected rapid intraoperative PTH (IOPTH) kinetics in these patients.

STUDY DESIGN: Retrospective cohort study.

SETTING: Department of Otolaryngology-Head and Neck Surgery, Henry Ford Health, Detroit, Mich.

SYNOPSIS: Researchers collected demographic, preoperative, intraoperative, and postoperative metrics on patients undergoing parathyroidectomy for HPT from July 2013 to February 2020. Two treatment groups and their respective controls were created. The NH Preop group met criteria for NHHPT based on a normal-range preoperative intact PTH; the NH Intraop group met criteria for NHHPT based on normal range, pre-incision IOPHT. Pre-, intra- and postoperative metrics were compared among the two NH groups and their respective controls. Of the 496 patients (80.3% female, median age 61.5 years) included, 66 (13.3%) had NHHPT based on normal, preoperative, intact PTH levels, and 28 (5.6%) had NHHPT based on baseline IOPTH levels. Cure rates in the two normohormonal groups did not differ significantly from those of their classical counterparts. The median percent decline in post-excision IOPTH from baseline that achieved cure in the normohormonal groups were 82.6% for the NH Preop group and 80.4% for the NH Intraop group, compared to their respective controls at 87.3%. Authors acknowledge that although NHHPT may be an indication of somewhat more challenging surgery, their results show that these cases can be performed with a high rate of success, while reliably employing IOPHT monitoring.

Study limitations included short follow-up times.

CITATION: Law RH, Larrabee KA, Stefan AJ, et al. Intraoperative parathyroid hormone monitoring in normohormonal primary hyperparathyroidism: How low do you go? Laryngoscope. 2024;134:2480–2484.