Abstract
Introduction/Objective
Histologic frozen section analysis is typically used for parathyroid tissue identification during parathyroidectomy when needed, in conjunction with a rapid intraoperative plasma parathyroid hormone (PTH) assay to confirm falling levels of circulating PTH after parathyroid excision. As an alternative to frozen section consults, we hypothesize that automated analysis of intraoperative fine needle aspiration (ioFNA) tissue samples using a rapid PTH immunoassay can accurately identify parathyroid tissue and reduce the need for frozen section consults.
Methods
A rapid PTH immunoassay (Elecsys PTH STAT; Roche Diagnostics, Indianapolis, IN), currently used for intraoperative plasma samples, was validated for FNA samples on a Cobas® e411 using tissue aspirates of ex vivo parathyroid and control specimens rinsed in 1mL saline. ioFNA PTH results during parathyroidectomy were then prospectively assessed for accuracy over a 4-month period by comparing values to final histopathologic diagnoses. The number of frozen section consults requested was compared to a 5-month period prior to the availability of the ioFNA PTH assay.
Results
Ninety patients underwent parathyroidectomy (128 excised parathyroids) during the study period, performed by a single experienced endocrine surgeon. Indications included primary (81/90), tertiary (5/90), and recurrent (4/90) hyperparathyroidism. Thirty-nine cases (55.5 excised parathyroids) were performed after the availability of the ioFNA PTH assay. ioFNA samples were sent for PTH analysis in 7/39 cases (18%; 12 samples total) and had a sensitivity/specificity of 100% (parathyroid [n=7] PTH values 1968 - >5000pg/mL; non-parathyroid [n=5] PTH values <2 - 16pg/mL). Parathyroidectomies requiring frozen section consult significantly decreased from 41% (21/51 cases; 40 specimens) to 10% (4/39 cases; 9 specimens) with the availability of the ioFNA PTH assay (p< 0.05, Fisher exact test).
Conclusion
Analysis of ioFNA tissue samples using an automated rapid PTH immunoassay can accurately identify parathyroid tissue and can be used as an alternative to frozen section consult when needed.
Role of fine-needle aspiration biopsy and frozen-section evaluation in the surgical management of thyroid nodules
