Diagnostic Efficiency of Thyroglobulin in Lymph Node Fine-needle Aspiration Washout: A Systematic Review and Meta-analysis.

[CONTEXT] Cervical lymph node metastases are common in papillary thyroid carcinoma (PTC), causing recurrence and poor regional control, highlighting the need for accurate diagnostics. Although fine-needle aspiration with thyroglobulin washout (FNA-Tg) shows promise, its diagnostic performance and association with serum biomarkers across settings remain unclear.

[OBJECTIVE] To assess the diagnostic performance of FNA-Tg for cervical lymph node metastases in PTC and its correlation with serum thyroglobin (s-Tg) and s-Tg antibody (s-Tg-Ab) levels.

[DATA SOURCES] PubMed, Embase, Web of Science, Scopus, Cochrane Library, and Ovid Medline were searched for relevant studies.

[STUDY SELECTION] Studies enrolling PTC patients with cervical lymphadenopathy who underwent FNA-Tg pre- or postthyroidectomy were included. Studies involving non-PTC populations or lacking sufficient data for 2 × 2 diagnostic table construction were excluded.

[DATA EXTRACTION] Data were independently extracted by 3 researchers, and study quality was assessed by the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

[DATA SYNTHESIS] FNA-Tg showed pooled sensitivity of 0.94 [95% confidence interval (CI), 0.91-0.96], specificity of 0.92 (95% CI: 0.88-0.94), and diagnostic odds ratio (DOR) of 174.20 (95% CI: 87.05-348.61), with an area under curve (AUC) of 0.98 (95% CI: 0.96-0.99). Postthyroidectomy, sensitivity increased to 0.96 (95% CI: 0.94-0.98), specificity to 0.93 (95% CI: 0.86-0.96), and DOR to 305.87 (95% CI: 127.99-730.93), with an AUC of 0.98 (95% CI: 0.97-0.99). In the group without thyroid gland present, sensitivity was 0.96 (95% CI: 0.93-0.97), specificity 0.93 (95% CI: 0.87-0.97), and DOR 300.27 (95% CI: 118.47-761.05), with an AUC of 0.98 (95% CI: 0.97-0.99). Likelihood ratio scattergrams and Fagan plots supported its discriminatory ability. FNA-Tg correlated weakly with s-Tg but not with s-Tg-Ab.

[CONCLUSION] FNA-Tg showed high diagnostic accuracy, especially after thyroidectomy, with minimal s-Tg-Ab interference, supporting its role in PTC surveillance.