Stricter criteria increase the validity of a quick intraoperative parathyroid hormone assay in primary hyperparathyroidism

Abstract

Background: A "quick" intraoperative parathyroid hormone (PTH) (QPTH) assay evaluates parathyroid hypersecretion during parathyroidectomy. We investigated the likelihood of increasing surgical success rates by introducing stricter parameters in intraoperative PTH monitoring.

Material/methods: One hundred one patients with sporadic primary hyperparathyroidism were studied. Intraoperative plasma intact PTH (iPTH) levels were measured with a modified 2-site antibody immunochemiluminometric assay. iPTH values were determined before the manipulation of parathyroid tissue (t-10') and then 3 (t+3') and 10 (t+10') minutes after resection of the suspected pathologic parathyroid gland(s).

Results: The median (interquartile range) baseline iPTH level was 259.6 (536) ng/L at t-10' and 64.1 (139.5) ng/L at t+10'. At t+3' and t+10', the median percentage decrease of iPTH from baseline was 56.1% and 77.3%, respectively. In 7 patients, the iPTH level decreased very slowly, and in patients with a double adenoma, an initial increase in the iPTH level occurred because of considerable manipulation during surgery. Despite a decrease of about 50% in iPTH level, persistent hyperparathyroidism was identified after a few months in 2 patients with a multiglandular pathologic condition in which a relatively larger parathyroid "masked" the hyperactivity of other parathyroid glands.

Conclusions: A QPTH is useful during parathyroidectomy. A decrease in the iPTH level of > or =70% from baseline indicates a successful operation and reduces the likelihood of false-positive results. The evaluation of more than 1 PTH level is required if multiglandular disease is suspected or excessive intraoperative manipulation occurs.