Surgical Management of Normocalcemic Primary Hyperparathyroidism and the Impact of Intraoperative Parathyroid Hormone Testing on Outcome.

Objective To review our surgical experience and the impact of intraoperative parathyroid hormone (IOPTH) testing among patients with normocalcemic primary hyperparathyroidism. Study Design Case series with chart review. Setting Academic referral hospital. Subject and Methods Normocalcemic hyperparathyroidism (NCHPT) patients were identified with normal-range blood ionized calcium and serum elevated parathyroid hormone. Patient demographics, intraoperative findings, IOPTH dynamics, and biochemical outcomes were compared with those of classic primary hyperparathyroidism (PHPT) patients. Results Of the 2120 patients who underwent parathyroidectomy, 616 patients met the inclusion criteria: 119 (19.5%) patients had NCHPT, and 497 (80.5%) had classic PHPT. NCHPT patients had higher rates of multigland hyperplasia as compared with classic PHPT (12% vs 4%, P = .002) and smaller gland size ( P < .001). Of 119 NCHPT patients, 114 (97%) achieved >50% drop in IOPTH intraoperatively, as opposed to 492 (99%) among 497 classic PHPT patients ( P = .014). IOPTH drop >50% had an equivalent positive predictive value for long-term cure in both groups. Conclusions Surgeons treating NCHPT patients should suspect the presence of multigland disease and have a low threshold for converting to bilateral exploration depending on IOPTH decay dynamics.