Aim: To evaluate the serum levels of resistin and adiponectin, and the potential relationship between these adipokines, thyroid function, lipid profile, C-reactive protein (CRP) and homocysteine levels in patients with autoimmune thyroiditis (AIT) and subclinical hypothyroidism (SCH).
Methods: patients with AIT (58 females; 47.7±16.7 years) were studied; 33 of them had also SCH. These patients were diagnosed by a positive result in an anti-peroxidase (anti-TPO) and anti-thyroglobulin antibodies, and a typical ultrasound pattern. Statistical analyses were done using the Student t-test, MannWhitney U test, and Spearmans rank correlation test. A two-tailed P value <0.05 was considered statistically significant.
Results: The patient subgroups were similar in age and sex distribution. The distribution of overweight (SCH=40.0 vs 36.7%) and obese (SCH=31.4 vs 23.3%) patients was not significantly different in the two subgroups. Patients with SCH had significantly higher levels of total (221.3±50.7 vs 199.1±39.3 mg/dl, P=0.03) and LDL-cholesterol (137.7±39.3 vs 125.5±57.1 mg/dl, P=0.02). In SCH subgroup, FT4 positively correlated with apoA1 (r=0.41, P=0.04) and HDL (r=0.48, P<0.01), and negatively correlated with LP(a) (r=−0.44, P=0.03). A significant correlation between homocysteine and triglycerides levels was found in patients with SCH (r=0.58, P<0.01). Both subgroups had similar levels of adiponectin and resistin. In the SCH subgroup we found a positive correlation between resistin and TSH (r=0.38, P=0.03).
In total group, CRP levels were positively correlated with anti-thyroglobulin (r=0.33, P<0.01) and resistin levels (r=0.34, P<0.01). In this group, adiponectin levels positively correlated with HDL-cholesterol (r=0.3, P=0.02) and resistin positively correlated with triglycerides levels (r=0.27, n=62, P=0.04).
Conclusion: Our study suggests that autoimmune thyroiditis, even at its early stages of subclinical hypothyroidism, is associated with an increased cardiovascular risk, given the changes in serum lipid levels and the correlations between thyroid function, CRP, serum lipids and adipokines levels.