Rapid intraoperative parathyroid hormone assay in fine needle aspiration for differential diagnosis in thyroid and parathyroid surgery.

Background: The purpose of our study was to investigate the efficacy of rapid intraoperative parathyroid hormone (rIO-PTH) analysis performed using material collected by fine needle aspiration as a parameter to distinguish anatomical structures which the surgeon is not able to identify clearly as parathyroid or lymph node during thyroid/parathyroid surgery. Before surgery, all patients gave written, informed consent. Methods: We measured the rIO-PTH on 50 anatomical structures, 32 presumed parathyroids and 18 presumed lymph nodes from 22 patients, who underwent thyroid/parathyroid surgery between May and September 2009. Results: The rIO-PTH values obtained on parathyroids ranged from 85.4 pmol/L to more than 2106 pmol/L, with a rIO-PTH median of 263.25 pmol/L. Results obtained on lymph nodes ranged from <0.52 pmol/L up to 20.4 pmol/L, with a rIO-PTH median equal to 1.31 pmol/L. Results of the Mann-Whitney test showed a rIO-PTH median significantly different (p<0.0001) between samples obtained from parathyroid glands and lymph node tissue. Conclusions: We demonstrated that rapid intraoperative measurement of parathyroid hormone is a good parameter for the differential diagnosis of parathyroid vs. lymph node tissue. We suggest extending the use of this technique to the field of parathyroid preservation during thyroid/parathyroid surgery in those cases where the parathyroids prove difficult to recognize on the basis of topographic or morphologic criteria.