Effects of thyroid autoimmunity on abdominal obesity and hyperlipidaemia

Thyroid autoimmunity has been suggested as a risk factor for atherosclerosis independent of thyroid function in several studies. The aim of this study was to investigate whether thyroid autoimmunity had any effect on hyperlipidaemia, obesity and abdominal obesity independent of thyroid function. 184 premenopausal female patients with Hashimoto's thyroiditis (HT) and 150 healthy premenopausal female volunteers as control group (CG) were included in the study. According to thyroid function status, the patients were divided into three subgroups: overt hypothyroid patients (ohp), subclinical hypothyroid patients (shp) and euthyroid patients (ep). Body mass index (BMI), waist to hip ratios, waist circumference (WC), and serum lipid levels of all the participants were determined. These parameters of ep were compared with those of ohp, shp and CG. Relationships among thyroid stimulating hormone (TSH), thyroid autoantibodies and lipid levels were investigated. There were no significant differences between serum total cholesterol and low density lipoprotein cholesterol (LDL-C) levels of ohp and ep with HT (P = 0.18, P = 0.07 respectively) and LDL-C levels of ep were higher than those of CG (P = 0.03, P = 0.042, respectively). Although TSH levels did not correlate with serum lipid levels, levels of anti-thyroid peroxidase antibody correlated with triglyceride levels and WCs (r = 0.158; P = 0.013, r = 0.128; P = 0.048 respectively) and negatively correlated with high density lipoprotein cholesterol (HDL-C) levels (r = -0.137; P = 0.031). Levels of anti-thyroglobulin antibody also correlated with triglyceride and nonHDL-C levels (r = 0.208; P = 0.007, r = 0.158; P = 0.043 respectively). Thyroid autoimmunity may have some effects on hyperlipidaemia and abdominal obesity independent of thyroid function.