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

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. 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). 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. 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.