{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,2]],"date-time":"2026-05-02T21:43:00Z","timestamp":1777758180945,"version":"3.51.4"},"reference-count":18,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T00:00:00Z","timestamp":1777420800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background: Fine-needle aspiration thyroglobulin (FNA-Tg) is widely used to detect lymph node metastases in differentiated thyroid cancer (DTC), but optimal cut-off values remain controversial. Anti-thyroglobulin antibodies (anti-Tg), present in 25\u201340% of DTC patients, may interfere with FNA-Tg measurements. This study aimed to evaluate whether anti-Tg status necessitates different FNA-Tg diagnostic thresholds in the preoperative setting. Methods: We retrospectively analyzed 605 cervical lymph nodes from 393 preoperative DTC patients who underwent ultrasound-guided fine-needle aspiration (FNA) with concurrent FNA-Tg measurement (February 2019\u2013April 2025). All lymph nodes had histopathological or cytological confirmation. Patients were stratified by anti-Tg status (&gt;4.5 IU\/mL). Receiver operating characteristic curve analysis determined optimal FNA-Tg cut-offs, and areas under the curve (AUCs) were compared using the DeLong test. Results: FNA-Tg demonstrated excellent overall diagnostic accuracy (AUC 0.963, 95% CI 0.946\u20130.980) with an optimal cut-off of 84.0 ng\/mL (sensitivity 91.6%, specificity 95.3%). Anti-Tg-positive patients had significantly lower FNA-Tg levels in malignant lymph nodes compared to anti-Tg-negative patients (median 9872 vs. 22,327 ng\/mL, p = 0.001). Subgroup analysis revealed superior performance in anti-Tg-negative patients (AUC 0.983, cut-off 84.4 ng\/mL) compared to anti-Tg-positive patients (AUC 0.923, cut-off 65.7 ng\/mL; p = 0.008). No significant correlation was observed between anti-Tg levels and FNA-Tg (\u03c1 = \u22120.03, p = 0.501). Conclusions: Anti-Tg status influenced measured FNA-Tg levels and receiver operating characteristic (ROC) derived optimal thresholds in the preoperative setting. However, because malignant lymph nodes generally showed FNA-Tg values well above the benign range, the clinical impact of this difference appears limited in most clearly positive cases. These findings may still help refine interpretation in selected borderline cases.<\/jats:p>","DOI":"10.3390\/diagnostics16091344","type":"journal-article","created":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T12:31:56Z","timestamp":1777465916000},"page":"1344","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Antibody-Stratified FNA-Thyroglobulin Cut-Off Values for Preoperative Lymph Node Assessment in Differentiated Thyroid Cancer"],"prefix":"10.3390","volume":"16","author":[{"given":"Beril","family":"Turan Erdogan","sequence":"first","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Bilkent City Hospital, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kubra","family":"Durmus Demirel","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Bilkent City Hospital, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fatma Dilek","family":"Dellal Kahramanca","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Bilkent City Hospital, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fazli","family":"Erdogan","sequence":"additional","affiliation":[{"name":"Department of Pathology, Faculty of Medicine, Ankara Yildirim Beyazit University, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yunus Nadi","family":"Yuksek","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Ankara Bilkent City Hospital, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cevdet","family":"Aydin","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Faculty of Medicine, Ankara Yildirim Beyazit University, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Oya","family":"Topaloglu","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Faculty of Medicine, Ankara Yildirim Beyazit University, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7437-1176","authenticated-orcid":false,"given":"Reyhan","family":"Ersoy","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Faculty of Medicine, Ankara Yildirim Beyazit University, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bekir","family":"Cakir","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Faculty of Medicine, Ankara Yildirim Beyazit University, 06800 Ankara, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"959","DOI":"10.1089\/thy.2004.14.959","article-title":"Detection of recurrent papillary thyroid carcinoma by thyroglobulin assessment in the needle washout after fine-needle aspiration of suspicious lymph nodes","volume":"14","author":"Baskin","year":"2004","journal-title":"Thyroid"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1364","DOI":"10.1210\/jc.2005-1705","article-title":"The diagnostic value for differentiated thyroid carcinoma metastases of thyroglobulin (Tg) measurement in washout fluid from fine needle aspiration biopsy of cervical lymph nodes is maintained in the presence of circulating anti-Tg antibodies","volume":"91","author":"Boi","year":"2006","journal-title":"J. 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