Resistin levels in hyperthyroid patients before and after restoration of thyroid function: Relationship with body weight and body composition

Background: Resistin is a recently discovered peptide hormone that belongs to a family of tissue-specific resistin-like molecules. To date, very few studies have reported on resistin concentrations in hyperthyroid patients, and they present controversial results. Objectives: To undertake a controlled, prospective study to investigate resistin concentrations in hyperthyroidism before and after restoration of euthyroidism and to correlate the results with body weight, body fat, waist circumference and body mass index (BMI). Patients and Methods: A total of 43 hyperthyroid patients (12 men and 31 women) were investigated, in addition to 23 controls. Anthropometric parameters and resistin concentrations were measured. All the patients commenced taking antithyroid drugs and 3-4 months later the same investigations were performed in 36 of the 43 individuals. Results: Hyperthyroid patients exhibited increased resistin concentrations in comparison with controls. Normalization of thyroid hormones was accompanied by a significant decrease in resistin concentration. A sex difference was also found, men showing a significant decrease in resistin concentrations, whereas in women no such difference was found. Resistin concentrations did not correlate with different anthropometric parameters, age and thyroid hormones, either before or after treatment. Conclusions: This study demonstrates for the first time that, although resistin concentrations are increased in hyperthyroidism, they are not associated with body weight, body fat, waist circumference or BMI, which makes it unlikely that resistin plays a crucial part in thermogenesis and energy homeostasis in thyrotoxic patients.