Association of Thyroid-Stimulating Hormone With Serum Insulin and High-Sensitivity C-Reactive Protein in Patients With Hypothyroidism

Background: Hypothyroidism is associated with metabolic disturbances that extend beyond abnormalities in thyroid hormone concentrations. Alterations in insulin metabolism and chronic low-grade inflammation may contribute to the increased cardiometabolic risk observed in patients with thyroid dysfunction. Thyroid-stimulating hormone (TSH) is routinely used to assess thyroid status; however, its relationship with serum insulin and high-sensitivity C-reactive protein (hs-CRP) requires further evaluation. Materials and Methods: This observational cross-sectional study included 300 patients with hypothyroidism. Demographic, clinical, anthropometric, and biochemical data were collected. Serum TSH, free thyroxine (FT4), serum insulin, and hs-CRP were estimated using standardized laboratory methods. Correlation analysis was performed to determine the relationship between serum TSH and metabolic and inflammatory parameters. A p-value <0.05 was considered statistically significant. Results: The study included 191 (63.7%) females and 109 (36.3%) males, with a mean age of 43.32 ± 12.53 years. The mean serum TSH concentration was 9.34 ± 5.35 mIU/L. The mean serum insulin concentration was 12.37 ± 4.62 µIU/mL, and serum TSH showed a statistically significant positive correlation with serum insulin (r = 0.184, p = 0.001). The mean hs-CRP concentration was 2.68 ± 1.65 mg/L. Serum TSH demonstrated a statistically significant positive correlation with hs-CRP (r = 0.264, p <0.001). Conclusion: Higher serum TSH concentrations were significantly associated with increased serum insulin and hs-CRP concentrations in patients with hypothyroidism. These findings suggest that increasing thyroid dysfunction may be associated with concurrent metabolic and inflammatory abnormalities.