The relationships between selected serum adipokines and thyroid function in patients with obesity

The study was designed to evaluate the effect of thyroid function on serum levels of different adipokines in obesity. We investigated relationships between the thyroid axis and serum levels of leptin, adiponectin, and chemerin, and we assessed the influence of autoimmune thyroiditis (AIT) on those relations.

The participants of this study included 181 euthyroid patients (147 women and 34 men) with obesity [body mass index (BMI) 30-39.9 kg/m²] and severe (morbid) obesity (BMI ≥ 40 kg/m²), aged 18 to 65 years. We divided all obese patients by thyrotropic hormone (TSH) tertiles, and we compared all participants according to BMI. Patients were further divided into the following subgroups: with chronic autoimmune thyroiditis and without autoimmune thyroiditis.

Comparison of obese patients according to TSH tertile showed significantly higher serum concentrations of leptin, chemerin, and thyroid antibodies and an increased leptin/adiponectin ratio in the group with high normal TSH. We observed statistically significant correlations between serum TSH and BMI, leptin, chemerin, thyroid peroxidase antibodies, and the leptin/adiponectin ratio. In patients diagnosed with autoimmune thyroiditis, higher levels of antibodies and TSH were found, but there were no differences in homeostatic model assessment index (HOMA-I), the leptin/adiponectin ratio, and adipokine levels. In obese patients the relationships between serum leptin, chemerin, the leptin/adiponectin ratio, and BMI were dependent on each other.

Serum leptin, chemerin, the leptin/adiponectin ratio, and BMI are significantly higher in patients with high normal TSH; however, selected adipokines are not related to the presence of autoimmune thyroiditis. There are interplays between TSH, adipokines, and obesity, but how these relationships are related remains unknown.