Determinants of Visfatin/NAMPT Serum Concentration and its Leukocyte Expression in Hyperthyroidism

We aimed to analyze the potential influence of thyroid autoimmunity on visfatin/NAMPT serum concentration and its leukocyte expression in hyperthyroid patients. This is a single-center, cross-sectional study with consecutive enrollment. All patients with newly diagnosed overt hyperthyroidism in a course of Graves' disease or toxic nodular goiter were included in the study. They underwent physical examination, laboratory investigation, body composition analysis, and thyroid ultrasound. NAMPT mRNA leukocyte expressions were measured using RT-qPCR. Of the 173 patients, 95 were enrolled in further analysis [67 patients with Graves' disease (GD) and 28 with toxic nodular goiter (TNG)]. Control group consisted of 43 healthy volunteers adjusted for age, sex, and BMI. Higher NAMPT/visfatin serum concentration was found in patients with GD comparing with patients with TNG (p=0.03855). We found significant NAMPT leukocyte overexpression in GD patients (n=32) as compared to TNG patients (n=18) and euthyroid controls (n=24) (p=0.005965). Simple linear regression analysis revealed that NAMPT/visfatin serum concentration was significantly associated with NAMPT leukocyte expression, thyroid autoimmunity, age, HOMA-IR, and fat mass percentage (FM%). NAMPT leukocyte expression was related to thyroid autoimmunity, age, and TRAb levels. The stepwise multiple regression analysis revealed FM% and HOMA-IR as independent predictors of visfatin/NAMPT serum levels. In a separate stepwise multiple regression analysis, we confirmed the association between NAMPT leukocyte expression and TRAb levels. We found that fat mass percentage together with HOMA-IR are the most significant predictors of visfatin/NAMPT serum elevation in hyperthyroid patients.