Lymph Node Thyroglobulin Measurement in Diagnosis of Neck Metastases of Differentiated Thyroid Carcinoma

Abstract

Aim. Enlarged cervical lymph nodes (LNs) in patients with thyroid cancer are usually assessed by fine-needle aspiration cytology (FNAC). Thyroglobulin (Tg) is frequently elevated in malignant FNAC needle wash specimens (FNAC-Tg). The objectives of the study were to (1) determine an appropriate diagnostic cut-off for FNAC-Tg levels (2) compare FNAC and FNAC-Tg results in a group of 108 patients affected by differentiated thyroid carcinoma (DTC). Methods. A total of 126 consecutive FNACs were performed on enlarged LNs and the final diagnosis was confirmed by surgical pathology examination or clinical follow-up. The best FNAC-Tg cut-off level was selected by receiver operating curve analysis, and diagnostic performances of FNAC and FNAC-Tg were compared. Results. The rate of FNAC samples adequate for cytological examination was 77% in contrast FNAC-Tg available in 100% of aspirates (P < .01). The sensitivity, specificity, and accuracy of FNAC were 71%, 80%, 74%, 100%, 80%, and 94%, respectively. The most appropriate cut-off value for the diagnosis of thyroid cancer metastatic LN was 1.1 ng/mL (sensitivity 100%, specificity 100%). Conclusions. The diagnostic performance of needle washout FNAC-Tg measurement with a cut-off of 1.1 ng/mL compared favorably with cytology in detecting DTC node metastases.

Optimized Cutoff Value and Indication for Washout Thyroglobulin Level According to Ultrasound Findings in Patients with Well-Differentiated Thyroid Cancer

“…One prior report suggested that the most appropriate cutoff value of FNA-Tg is 1.1 ng/mL, 12 and another study yielded a cutoff value of 5 ng/mL. 13 The result of our study, 1.8 ng/mL, was between the 2 reports.…”

Measurement of thyroglobulin, calcitonin, and PTH in FNA washout fluids

“…Snozek and colleagues [19] measured FNA-Tg in 122 samples from 88 athyreotic DTC patients, using immunochemiluminometric assay (CLIA) with functional sensitivity of 0.1 μg/L; 50/52 nonmalignant samples (96.2%) had values ≤ 1 μg/L and 70/70 malignant lesions had levels > 1 μg/L. By a different high-sensitivity immunoradiometric assay (IRMA) (functional sensitivity 0.2 μg/L) and adopting a ROC derived cutoff of 1.1 μg/L, the authors of the present review obtained 100% sensitivity, specificity, and accuracy [34]. These results were subsequently confirmed in a large-scale study including 528 cases of FNA-Tg patients [24].…”

Thyroglobulin Wash Testing in the Surveillance of Patients with Thyroid Carcinoma: Proposal for a Reflex Test

“…It is used for both lymph nodes and thyroid bed nodules. The recommendations to add TG-W testing to FNA cytology are based on strong evidence of increased sensitivity of combined testing over cytology alone [2,6,8,10,12,14]. Positive FNA cytology in cervical lymph nodes at the time of initial investigation for DTC will necessitate the extension of the surgery to include the involved group of lymph nodes [1].…”