Predictive Value of TSH for Cardiovascular Risk Markers in Subclinical Hypothyroidism: Focus on CRP, AIP, and HbA1c

Background. Subclinical hypothyroidism (SCH) may increase cardiovascular risk through early alterations in inflammation (hs-CRP), atherogenicity (AIP), and glycemic status (HbA1c). This study aimed to evaluate the association and discriminatory ability of thyroid-stimulating hormone (TSH) with these cardiovascular risk markers in individuals with subclinical hypothyroidism (SCH). Methods. A comparative case-control study was performed with 76 patients diagnosed with SCH and 72 healthy controls matched for age and sex. Anthropometric and biochemical parameters were evaluated, including thyroid hormones (TSH, FT3, FT4), anti-thyroid peroxidase (anti-TPO) antibodies, lipid profile, hs-CRP, AIP, fasting blood glucose (FBG), and HbA1c. Correlations between thyroid markers and cardiovascular risk indicators (hs-CRP, AIP, HbA1c) were examined using Spearman’s correlation, binary logistic regression, and receiver operating characteristic (ROC) curve analysis. Results. SCH patients exhibited markedly elevated levels of total cholesterol, triglycerides, LDL, VLDL, and AIP compared with controls (p < 0.05), whereas HDL, fasting blood glucose, and HbA1c showed no significant differences. Although hs-CRP levels did not differ significantly between groups (p = 0.061), TSH was positively correlated with hs-CRP (r = 0.343, p = 0.002) and AIP (r = 0.235, p = 0.041). Multiple regression analysis identified TSH as an independent determinant of hs-CRP after adjustment for potential confounding variables. ROC analysis demonstrated improved discriminatory performance for hs-CRP after adjustment, with the AUC increasing from 0.747 to 0.838 (ΔAUC = 0.0906, p = 0.0227), supporting the association of TSH with inflammatory status in SCH. Conclusions. In SCH, elevated TSH is linked to the early inflammatory and atherogenic changes indicated by hs-CRP and AIP. These findings support the use of TSH as a simple and cost-effective indicator for cardiovascular risk stratification in SCH. Regular monitoring of hs-CRP and AIP may enable the early identification of high-risk patients, while forthcoming prospective trials should evaluate whether early normalization of TSH can reduce inflammation and enhance cardiovascular outcomes.