Abstract
BACKGROUND: Intraoperative parathyroid hormone (IOPTH) monitoring is crucial in the treatment of primary hyperparathyroidism (PHPT). Often, the 5 min IOPTH levels fall, but not by the requisite 50 %. In such cases, the surgeon must decide whether to wait for additional levels or to continue exploration. This study aimed to evaluate the 5 min drop in IOPTH for distinguishing single adenomas (SA) from multigland disease. METHODS: A retrospective analysis of a prospectively collected database was performed on PHPT patients who underwent initial curative parathyroidectomy between 2001 and 2013. Those with familial disease and those taking lithium or undergoing concomitant thyroidectomy were excluded from the analysis. For cases of double adenomas (DA) or hyperplasia (HA), the IOPTH values indicating additional glands were analyzed. RESULTS: The inclusion criteria were met by 1021 patients: 817 patients with SA (82.2 %), 99 patients with DA (10 %), and 78 with HA (7.9 %). The SA patients exhibited a 56.6 ± 4.9 % decline in IOPTH at 5 min compared with 21.3 ± 4.5 % of the DA patients and 22.5 ± 4.3 % of the HA patients (p < 0.01). Post hoc comparisons showed that the 5 min decrease in the SA group was significantly greater than in either the DA group or the HA group (p < 0.01). A 5 min percentage decline of 35 % best distinguished SA from multiglandular disease (85.3 vs. 24.9 %). CONCLUSION: The data suggest that when IOPTH level does not drop by at least 35 % at 5 min after excision, the surgeon should consider further exploration rather than wait for additional levels.