Background: Hashimoto’s thyroiditis (HT) is a chronic autoimmune thyroiditis that causes systemic inflammation in the body, leading to hypothyroidism and an enlargement of the thyroid gland. Objectives: This study aims to reveal whether there is a relationship between Hashimoto’s thyroiditis and the platelet-count-to-lymphocyte-count ratio (PLR), which is used as a new inflammatory marker. Methods: In this retrospective study, we compared the PLR of the euthyroid HT group and the hypothyroid-thyrotoxic HT group to the controls. We also evaluated the values of thyroid-stimulating hormone (TSH), free T4 (fT4), C-reactive protein (CRP), aspartate transaminase (AST), alanine transaminase (ALT), white blood cell count, lymphocyte count, hemoglobin, hematocrit, and platelet count in each group. Results: The PLR of the subjects with Hashimoto’s thyroiditis was found to be significantly different from the control group (p < 0.001), with the rankings as follows: hypothyroid-thyrotoxic HT 177% (72–417) > euthyroid HT 137% (69–272) > control group 103% (44–243). In addition to the increased PLR values, an increase in CRP values was also observed, revealing a strong positive correlation between the PLR and CRP in the HT patients. Conclusion: In this study, we found out that the PLR was higher in the hypothyroid-thyrotoxic HT and euthyroid HT patients than in a healthy control group.

Background: The aim of the study was assessing the De Ritis score, an inflammatory marker, in Hashimoto's thyroiditis (HT) patients which is characterized with autoimmunity and chronic inflammation.Methods: Between October 2021 and October 2022, the subjects in our outpatient clinics diagnosed with thyroiditis and healthy controls enrolled to the study. Age, gender, and laboratory parameters including C‐reactive protein (CRP), alanine (ALT), and aspartate (AST) transaminases, thyroid stimulating hormone (TSH), free T4 (FT4), were obtained and recorded for all participants, retrospectively. Division of AST by ALT was the formula to calculate the De Ritis score. Characteristics and laboratory data of the study and healthy controls were compared.Results: Median de Ritis ratio of the HT group (1.11 (0.56)%) was significantly higher than that of the control group (0.91 (0.41)%), (p < .001). A positive and significant correlation between De Ritis score and CRP (r = 0.46, p < .001) values. ROC analysis revealed the sensitivity and the specificity of CRP in predicting HT were higher than those of the De Ritis score. A De Ritis score higher than 0.9% has 67% sensitivity and 50% specificity in selecting patients with thyroiditis (AUC: 0.69, p < .001, 95% CI: 0.63–0.76).Conclusions: We think that elevated De Ritis score can be used as an adjunctive tool in the diagnosis of HT.