Objective: Thyroid hormone affects adipocyte function, which in turn influences lipid and carbohydrate metabolism. Adiponectin is one of the adipocytokines that regulates lipid and carbohydrate metabolism. The aim of our study was to evaluate circulating levels of adiponectin in patients with thyroid dysfunction before and after normalization of thyroid function with appropriate medication.
Design & methods: One hundred and twenty patients with hyperthyroidism were recruited at the time of diagnosis. Measurements of free T4 (FT4), thyroid-stimulating hormone (TSH), thyrotropin binding inhibitor immunoglobulin (TBII), adiponectin, fasting blood glucose, fasting serum insulin, lipid profile, and body mass index (BMI) were taken before and after 6 months of medical treatment, at which point all patients were in a euthyroid state.
Results: Any change in BMI was strongly correlated with changes in serum-adiponectin levels (r = -0.789, p<0.001). Any change in serum FT4 was also correlated with changes in BMI and serum adiponectin levels (r = -0.254, p = 0.05 and r = 0.501, p = 0.029 respectively). After controlling for BMI changes, we found correlation also between serum FT4 and adiponectin (r = 0.29, p = 0.005). Multivariate-regression analysis still revealed BMI to be a statistically strong predictor for serum-adiponectin level (p<0.001). However, that analysis also revealed thyroid function level as another predictor (p = 0.029).
Conclusions: Although BMI is the best predictor of adiponectin, that thyroid hormone might influence circulating levels of adiponectin.