C‐reactive protein to LymphocytE count ratio could be a reliable mArkeR of thyroiditis; the CLEAR‐T study

Inflammation of the thyroid gland is referred to as thyroiditis and is associated with inflammation. Recent studies found significant association between thyroiditis and novel inflammatory and metabolic markers, as well as C‐reactive protein (CRP). CRP/lymphocyte count ratio (CLR) is a novel inflammatory marker that associated with various conditions and has not been studied in thyroiditis, yet. We aimed to investigate CRP to lymphocyte count ratio in patients with thyroiditis and to compare to those in healthy subjects. Patients with thyroiditis that presented to internal medicine outpatient clinics of our institution between January 2019 and August 2021 were enrolled to the retrospective study. Healthy volunteers were enrolled as control group. CLR of the thyroiditis and control groups were compared. Median CLR of the thyroiditis and control groups were 3.14 (0.14%–38)% and 0.4 (0.03–8.86)%, respectively (p < .001). The sensitivity and specificity of CLR > 0.43% in detecting thyroiditis were 92% and 58%, respectively (AUC: 0.88, p < .001, 95% CI: 0.85–0.92).CLR was significantly and positively correlated with free T4 (FT4) (r = .18, p < .001) and inversely correlated with thyroid stimulating hormone (TSH) (r = −.52, p = .003) levels. In conclusion, we suggest that high CLR levels may yield additional diagnostic value in patients with thyroiditis.