CLINICAL USEFULNESS OF AN INTRAOPERATIVE QUICK PARATHYROID-HORMONE ASSAY

Background. Intraoperative assays of parathyroid hormone (PTH) in the surgical management Of hyperparathyroidism have been limited by an ext ended ''turnaround'' time, making it impractical for the operating sur geon. With our modification of a standard immunoradiometric assay for intact PTH, results are reported in 12 minutes. The operative usefulne ss and the ability of this ''quick'' PTH'' assay to predict postoperat ive serum calcium levels are reported here. Methods. Quick PTH levels from whole blood samples taken 10 minutes after excision of hyperfunct ioning parathyroid glands were compared with preoperative and preexcis ion samples in patients undergoing 63 parathyroidectomies. Patients we re divided into two groups with assay incubation times of 10 and 6 min utes. The latter was clearly not sensitive enough and resulted in a 20 % false-negative rate. However, with a 10-minute incubation time, a de crease of 54% or more in quick PTH levels resulted in postoperative no rmocalcemia in patients with primary hyperparathyroidism. Results. Wit h these criteria used to predict the postoperative return to normocalc emia in 29 patients with primary hyperparathyroidism, the quick PTH as say had a sensitivity of 96%, specificity of 100%, and overall accurac y of 97%. Conclusions. The quick PTH assay was especially helpful in p redicting postoperative calcium levels when multiple excisions were ne cessary to remove all hyperfunctioning tissue or some normal parathyro id glands were not visualized.