Visfatin, Leptin, and TNF-α: Interrelated Adipokines in Insulin-Resistant Clinical and Subclinical Hypothyroidism

Purpose. This study is designed to evaluate the interrelationships among adipokines-visfatin, leptin, and tumor necrosis factor-alpha (TNF-alpha)- and insulin resistance (IR) in overt (n = 40) and subclinic hypothyroid (n = 25) patients and compare our findings with sex and body mass index-matched healthy controls (n = 25). Methods. Serum visfatin, leptin, and TNF-alpha levels were measured by enzyme-linked immunosorbent assay and C-reactive protein by immunoturbidimetry. Thyroid status (TSH, FT3, FT4) and lipid status (triglyceride, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, total cholesterol) parameters were measured. IR was determined by homeostatic model assessment (HOMA-IR) and McAuley (McA) indices. Results. HOMA-IR (p < 0.05) and McA indices (p < 0.01) revealed the presence of IR in overt hypothyroid patients. C-reactive protein, TNF-alpha, leptin, and visfatin levels were significantly higher (p < 0.01, p < 0.01, p < 0.001, and p < 0.001) in overt hypothyroid patients than euthyroid control group. Subclinic hypothyroid patients were observed to have significantly higher leptin and visfatin levels (p < 0.05) than euthyroid control group. In overt hypothyroid patients, we found plasma visfatin to be significantly positively correlated with HOMA-IR index (r = 0.336, p < 0.05) and body mass index (r = 0.445, p < 0.01) and negatively correlated with McA index (r = -0.574, p < 0.01). Conclusion. This study demonstrates the presence of IR in overt hypothyroid patients by HOMA and McA indices. Increased levels of visfatin, leptin, and TNF-alpha in overt and subclinic hypothyroid patients and the correlations among these adipokines highlighten their crucial role in the IR-associated disorders.