Abstract:Objective To analyze the diagnostic significance of preoperative neutrophil-to-lymphocyte ratio (NLR) for papillary thyroid microcarcinoma (PTMC) in elderly patients with Hashimoto′s thyroiditis (HT). Methods The clinical data of 120 elderly HT patients with thyroid nodules admitted in our hospital from March 2018 to January 2020 were collected and retrospectively analyzed. According to their postoperative pathological results, these patients were divided into PTMC+HT group (60 cases) and thyroid benign nodules+HT group (60 cases). SPSS statistics 26.0 was used for statistical analysis. Student′s t test or Chi-square test was employed for intergroup comparison depending on data type. Spearman correlation analysis was applied to analyze the correlation of NLR, neutrophil count and lymphocyte count with the benignancy or malignancy of thyroid nodules. Receiver operating characteristic (ROC) curve was plotted to evaluate the significance of NLR for the diagnosis of PTMC in elderly HT patients. Results Significant differences were observed in neutrophil count [(3.57±0.99)×109/L vs (2.95±1.00)×109/L], lymphocyte count [(1.89±0.41)×109/L vs (2.19±0.62)×109/L], and serum free thyroxine (FT4) level [(16.40±2.18) vs (15.17±2.35 pmol/L] between the PTMC+HT group and benign nodules+HT group (P<0.05). NLR and neutrophil count were positively correlated (r=0.478,0.301; P<0.05), while lymphocyte count was negatively correlated (r=-0.240, P=0.008) with benign and malignant thyroid nodules, with cut-off value of 1.44, the area under the curve (AUC) of NLR in the diagnosis of PTMC in the elderly HT patients was 0.776, with a sensitivity of 85% and a specificity of 60%. Conclusion NLR can be used as one of the indicators for differentiating benign and malignant thyroid nodules in elderly patients with HT. With the increase of NLR, it is more likely to diagnose malignant thyroid nodules, which provides a certain guiding significance for clinicians in screening, diagnosis and treatment of the disease.