Abstract
Introduction: Thyroid function and autoimmunity has been associated with cardiovascular events in patients with autoimmune thyroiditis. Objectives: To evaluate the association between thyroid function, antithyroid antibodies levels, insulin resistance and markers of cardiovascular risk in patients with autoimmune thyroiditis. Methods: We evaluated 228 patients with autoimmune thyroiditis, 93.9 % female, with a mean age of 47.06 ± 15.35 years. We analyzed thyroid function, anti-thyroglobulin antibodies (anti-Tg), anti-thyroid peroxidase antibodies (anti-TPO), HOMA-IR, HOMA-B, QUICKI, HISI (Hepatic Insulin Sensitivity Index), WBISI (Whole-Body Insulin Sensitivity Index), the levels of lipid profile, high-sensitivity C-reactive protein (hs-CRP), homocysteine, folic acid, and vitamin B12. We defined 3 groups based on TSH levels: TSH between 0.35-2.49 µUI/ml, (n = 166), TSH between 2.50-4.94 µUI/ml, (n = 43) and TSH over 4.95 µUI/ml, (n = 19), and normal levels of free T4 and free T3. A 75-g OGTT was performed in the morning and blood samples were obtained every 30 min for 120 min for measurements of plasma glucose, insulin, and C-peptide. For the statistical analysis we used the Mann-Whitney test and Spearman correlations. Results are expressed as means ± SD or percentages. A two-tailed p<0.05 was considered statistically significant. Results: There were no significant differences regarding median age or median BMI between groups. We did not find any significant differences comparing group with TSH 0.35-2.49 and group with TSH 2.50-4.94, in all parameters evaluated. Group with TSH 2.50-4.94 had higher indexes of QUICKI (0.69 ± 0.39 vs 0.48 ± 0.13; p = 0.02) and HISI (79.83 ± 63.72 vs 41.73 ± 29.02; p = 0.01) than group with TSH over 4.95. The group with TSH over 4.95 demonstrated a higher index of HOMA-IR than group with TSH 2.50-4.94 (3.77 ± 2.93 vs 1.95 ± 1.24; p = 0.01). In the TSH 0.35-2.49 group we found significant correlations between TSH and HOMA-IR (r= 0.18; p = 0.01), total cholesterol and anti-TPO (r =0.23; p = 0.002), anti-Tg and HDL-cholesterol (r= -0.17; p=0.002), anti-Tg and triglycerides (r=0.34; p < 0.001), and anti-Tg and LDL-cholesterol (r=0.16; p=0.03). In the TSH 2.50-4.94 group we observed positive correlation between Apo A1 and HOMA-B (r=0.58; p<0.001), HOMA-IR and LDL-cholesterol (r=0.34; p=0.02) and WBISI and HDL-cholesterol (r=0.34; p=0.02). In the TSH over 4.95 group we observed a correlation between TSH and triglycerides (r=0.70; p<0.001) and between anti-Tg and hs-CRP (r=0.64; p=0.004). Conclusions: The association among TSH, lipid profile, insulin resistance, hs-CRP and antithyroid antibodies in patients with autoimmune thyroiditis may contribute to an increased cardiovascular risk, not only in patients with subclinical hypothyroidism but also in those classified as euthyroid.
Lipid profile, insulin resistance and cytokines evaluation in autoimmune thyroiditis patients
