Preoperative localization of suspicious parathyroid adenomas by assay of parathyroid hormone in needle aspirates

Objective: To determine the usefulness of parathyroid hormone (PTH) measurement in needle aspirates of a suspicious neck mass to confirm its parathyroid nature in patients with primary hyperparathyroidism. Methods: Thirty-three patients with surgically proved primary hyperparathyroidism were submitted to neck ultrasound (US), parathyroid scintigraphy, and assay of PTH in the aspirate (PTHa) of the suspicious cervical mass. Results: Based on the results of neck US and parathyroid scintigraphy, patients were divided into two groups. Group 1: 16 patients (seven with nodular goiter) with concordant positive US and scintigraphic results. In all but one patient, PTHa was detectable and often markedly elevated (>1000 pg in 12 patients, between 292 pg and 803 pg in three patients and 53 pg in one patient). The patient with undetectable PTHa had a small lower left parathyroid adenoma (8x8x10 mm). Group 2: 17 patients (12 with nodular goiter) with discordant US and scintigraphic results, PTHa established the parathyroid nature of the mass in 13 cases (>1000 pg in 8 patients, between 501 pg and 953 pg in three patients and 90 and 79 pg in two patients): 11 of these had a suspected lesion by US examination but the scintigraphy results were negative; two had a mass that gave positive scintigraphy results but was of uncertain origin according to US: in both cases an intrathyroidal parathyroid adenoma was found. PTHa was undetectable in four cases (three with nodular goiter): all of these had equivocal US results, and three had positive scans and one a negative scan. Conclusions: Assay of PTHa is a simple method and should be useful for confirming the parathyroid nature of a cervical mass in patients with discordant or non-diagnostic US and scintigraphic results.