Applicability of tissue aspirate for quick parathyroid hormone assay to confirm parathyroid tissue identity during parathyroidectomy for primary hyperparathyroidism

Abstract

Hypothesis: Intraoperative quick parathyroid hormone (PTH) assay for tissue aspirate facilitates the confirmation of parathyroid tissue identity and allows a more selective use of frozen section examination during parathyroidectomy for primary hyperparathyroidism. Design: A retrospective review of a prospective protocol of the applicability and accuracy of quick PTH assay for tissue aspirate as a biochemical frozen section tool. Setting: A university hospital department of surgery. Patients: Quick PTH assay for aspirate obtained from suspected parathyroid gland excised during parathyroidectomy for primary hyperparathyroidism. Main Outcome Measures: The accuracy of this biochemical identification of parathyroid tissue identity was correlated with histological examination and outcome. Results: Quick PTH assay was performed for aspirate from at least 1 excised parathyroid gland in 122 (98%) of 125 patients while 13 patients (10%) had PTH aspirate for nonparathyroid tissues including thyroid (n = 10), thymic (n = 2) and lymphatic (n = 1) tissues. Frozen section examination was performed for 15 patients (12%), including the 3 patients who did not undergo tissue aspirate for quick PTH assay. All except 3 patients had an aspirate assay value of greater than 1500 pg/mL (range, 625 to >1500 pg/mL) for parathyroid tissue while the value of PTH aspirate for nonparathyroid tissue ranged from 27 to 229 pg/mL (median, 72 pg/mL) in 13 patients. The median size of abnormal parathyroid gland was 70 to 15000 mg (median, 775 mg). Conclusions: With the availability of quick PTH assay, tissue aspirate for PTH assay can be adopted as an alternative to traditional frozen section examination to confirm parathyroid gland identity. Frozen section examination can be employed more selectively.