Exploring Serum Anti-thyroid Peroxidase Antibodies and High-Sensitivity C-reactive Protein as Inflammatory Markers in...

Background and aim Subclinical hypothyroidism (SCH) is a biochemical condition defined by elevated thyroid-stimulating hormone (TSH) levels with normal free thyroxine (FT4) levels, often occurring without overt clinical symptoms. Emerging evidence suggests a role for autoimmune and inflammatory processes, with anti-thyroid peroxidase antibodies (anti-TPO) and high-sensitivity C-reactive protein (hsCRP) as potential markers of thyroid autoimmunity and systemic inflammation. This study evaluates the significance of these markers in SCH to elucidate their association with disease progression and clinical symptoms. This study aims to assess the roles of anti-TPO and hsCRP as inflammatory markers in SCH and to examine their correlations with clinical symptoms, lipid profiles, and cardiovascular risk, to stratify patients based on their autoimmune and inflammatory profiles. Methodology A retrospective, cross-sectional study was conducted on 220 patients, including 170 diagnosed with SCH and 50 euthyroid controls. Patients were categorized into SCH with anti-TPO positivity (SCH+), SCH without anti-TPO positivity (SCH-), and euthyroid controls. Serum TSH, FT4, anti-TPO, and hsCRP levels were analyzed using chemiluminescent immunoassay (CLIA), enzyme-linked immunosorbent assay (ELISA), and turbidimetric immunoassay. Statistical analyses, including Kruskal-Wallis and correlation tests, evaluated associations between hsCRP, anti-TPO, and clinical parameters. Results SCH+ participants demonstrated significantly higher levels of TSH (7.6 ± 2.1 mIU/L), hsCRP (4.2 ± 1.6 mg/L), and anti-TPO antibodies (116.5 ± 34.8 IU/mL) compared to SCH- and controls (P < 0.001). hsCRP was elevated in 52.2% of SCH+ individuals, indicating a systemic inflammatory state, compared to 32.1% in SCH- and 16% in controls. Significant correlations were observed between hsCRP and TSH (r = 0.62, P < 0.001) and between hsCRP and anti-TPO (r = 0.58, P < 0.001) in SCH+ participants. SCH+ patients exhibited a higher prevalence of fatigue, cold intolerance, and lipid abnormalities, with total cholesterol and LDL levels markedly elevated compared to other groups. Conclusions Anti-TPO and hsCRP are valuable markers for identifying systemic inflammation and autoimmune activity in SCH, particularly in anti-TPO-positive individuals. Their integration into routine evaluation may help stratify SCH patients based on cardiovascular and metabolic risk, guiding early therapeutic interventions. Further, longitudinal studies are needed to explore their prognostic value and therapeutic implications.