Clinical Benefits of Established Cut-off Value for Thyroglobulin Washout Concentration Used for Selecting Patients for Lymphadenectomy Due to Cervical Lymph Node Metastases of Differentiated Thyroid Cancer.

<b>

Introduction

</b> The cut-off value for fine needle aspiration thyroglobulin (FNA-Tg) was established at the level of 4.34 ng/mL (for the IRMA Brahms DYNO test) with a sensitivity of 91% and a specificity of 80-97% in detecting cervical lymph node metastases of differentiated thyroid cancer (DTC). <br><br><b>Aim:</b> The aim of this study was to evaluate the clinical benefits of the established FNA-Tg cut-off value used for selecting patients for lymphadenectomy. <br><br><b>Materials and methods:</b> The study included 33 patients after total thyroidectomy with elective and, in some cases, also selective cervical lymphadenectomy. The majority of patients also underwent subsequent 131I ablative therapy. The patients presented with 1-5 enlarged and/or ultrasonographically suspicious cervical lymph nodes. Fine needle aspiration biopsy (FNAB) was performed, taking 1-4 aspirates of each lymph node, with a total of 130 samples from 80 lymph nodes. All of the 33 patients were reoperated based on malignant fine needle aspiration biopsy cytology (FNAB-C) and/or FNA-Tg >4.34 ng/mL. <br><br><b>

Results

</b> DTC metastases were confirmed in at least one lymph node excised from each patient. Thirteen patients (39.4%) achieved clinical benefit from proper selection for surgery based on the established FNA-Tg cut-off value. Two patients (6.1%) would have been misdiagnosed if FNA-Tg had been the solitary criterion for surgery. <br><br><b>

Conclusions

</b> The use of the established FNA-Tg cut-off value (4.34 ng/mL) enables proper selection for lymphadenectomy due to DTC metastases. Measurement of FNA-Tg facilitates the diagnosis of recurrent/persistent DTC. It is recommended to take more than one FNAB sample and use both FNAB-C and FNA-Tg to diagnose and select patients for lymphadenectomy due to cervical lymph node metastases of DTC. <br><br><b>The authors' contribution to the development of the field:</b> The study is significant for the development of proper selectionfor lymphadenectomy due to cervical lymph node metastases of DTC.