Serum concentrations of leptin, adiponectin, and interleukin-6 in postmenopausal women with Hashimoto's thyroiditis

Leptin and adiponectin are involved in the pathogenesis of several autoimmune diseases. Very little is known about adipocytokine production in autoimmune thyroid diseases. Interleukin-6 (IL-6) plays an important role in the inflammatory and autoimmune processes.

The aim of this study was to assess the serum levels of leptin, adiponectin, and IL-6 in postmenopausal euthyroid women with Hashimoto's thyroiditis and compared them with concentrations in control women. Ninety-eight euthyroid women with Hashimoto's thyroiditis were enrolled in the study. The diagnosis was confirmed with elevated thyroid peroxidise autoantibody (TPOAb) levels in serum and typical hypoechogenic pattern on thyroid ultrasound. The control group, matched for body mass index (BMI), consisted of 105 healthy postmenopausal euthyroid women. Serum levels of leptin, adiponectin, IL-6, thyroid-stimulating hormone (TSH), free thyroxine (fT(4)), and TPOAbs were determined.

When compared with controls, the women with Hashimoto's thyroiditis were characterized by significantly elevated serum concentrations of IL-6, whereas concentrations of leptin and adiponectin were not different. Hashimoto's thyroiditis patients had significantly higher serum levels of TSH than the controls. The simple linear regression analyses of the Hashimoto's thyroiditis group and all of the studied women indicated that serum leptin levels correlated positively with BMI, waist to hip ratio (WHR), TSH, and IL-6 and negatively with adiponectin. No correlation was observed between serum adiponectin and TSH, fT(4), or TPOAbs. There were no associations between serum IL-6 levels, TPOAbs, and TSH levels; however, positive correlations between IL-6 and BMI, WHR, and leptin were observed. TSH correlated positively with leptin, age, and TPOAbs.

Hashimoto's thyroiditis is characterized by an increased production of IL-6 but does not have a direct influence on leptin or adiponectin serum levels. The correlations between TSH and leptin demonstrated in this study highlight the need for future investigations. (Pol J Endocrinol 2010; 61 (1): 112-116).