visfatin , also known as nicotinamide phosphoribosyltransferase ( nampt ) as well as pre - b - cell colony - enhancing factor , is a multifaceted protein with suggested enzymatic , immunological , and metabolic properties . visfatin has been analyzed in hypo- and hyperthyroidism in in vitro and in vivo studies , but results are inconclusive . in addition , nampt level was found to be elevated in many autoimmune diseases , that is , rheumatoid arthritis , systemic lupus erythematosus , inflammatory bowel diseases , and psoriasis [ 25 ] . visfatin also positively correlates with activity and severity of rheumatoid arthritis and psoriasis [ 2 , 5 ] . we have recently found an overexpression of nampt in leukocytes of patients with graves ' ophthalmopathy with corresponding increased serum concentration ( accepted manuscript ) . our findings suggest that visfatin might be involved in autoimmune processes in thyroid diseases . in our opinion , the controversial findings of visfatin in thyroid hormone deficiency may arise from the heterogeneity of thyroid dysfunction . we hypothesized that regulation of visfatin in hypothyroidism might be altered by coexisting chronic autoimmune thyroiditis , since high visfatin levels were observed in other autoimmune diseases . to answer the question about the influence of coexisting chronic autoimmune inflammation on visfatin level , we analyzed its serum concentration among hypothyroid patients with chronic autoimmune thyroiditis and in patients after thyroidectomy , who were negative for thyroid antibodies . this is a prospective case - control study of 118 subjects . the autoimmune study group ( ait ) consisted of 39 patients newly diagnosed with hypothyroidism in a course of chronic autoimmune thyroiditis . the nonautoimmune study group ( tt ) consisted of 40 patients thyroidectomized due to the differentiated thyroid cancer staged pt1 . tt patients were evaluated five years after radioiodine remnant ablation and were negative for thyroglobulin and radioiodine uptake in a whole body scintigraphy ( wbs ) . they achieved endogenous tsh stimulation and became hypothyroid after l - t4 withdrawal for at least 4 weeks . the control group comprised 39 healthy volunteers adjusted for age , sex , and bmi with normal thyroid function and negative thyroid antibodies . exclusion criteria consisted of other autoimmune diseases , active neoplastic disease , diabetes mellitus , and infection , which were reported to alter visfatin level . fasting blood samples were taken for visfatin , tsh , free thyroxine ( ft4 ) , free triiodothyronine ( ft3 ) , antithyroperoxidase antibodies ( tpoab ) , antithyroglobulin antibodies ( tgab ) , glucose , and insulin levels . in tt group tsh , ft4 , and ft3 were measured using the electrochemiluminescence technique in cobas e 601 ( norm ranges : tsh 0.274.2 tpoab and tgab were measured by radioimmunoassay ( norm range : < 34  iu / ml and < 115  iu / ml , resp . ) . glucose level was assessed with the use of hitachi cobas e601 chemiluminescent analyzer ( roche diagnostics ) and insulin concentration was assessed using elisa kit from phoenix pharmaceuticals . the estimate of insulin resistance by homeostasis model assessment ( homa - ir ) was calculated . the study was approved by the local ethics committee , and informed consent was signed by every subject . statistical analysis was performed with medcalc version 12.1.3.0 ( medcalc software , mariakerke , belgium ) . variables with normal distribution were compared between three groups with one - way analysis of variance . if data did not follow normal distribution , comparison of the analyzed parameters between three groups was performed with the kruskal - wallis test . simple regression analysis was used to test for the relationships between them . before inclusion to this statistical analysis , furthermore , stepwise multiple regression analysis was employed to investigate the influence of various parameters on visfatin serum concentration [ age , bmi , ft3 , autoimmunity ( yes / no ) , homa - ir ] . variables were entered into the model if their associated p - values were less than 0.05 and then sequentially removed if their associated p - values became greater than 0.2 . tests were considered to be statistically significant if p - value was lower than 0.05 . clinical and laboratory data of the study groups and the control group are shown in table 1 . the highest visfatin serum concentration was in ait group , and healthy controls had visfatin level higher than tt ( p = 0.0001 ) ( figure 1 ) . three groups did not differ in age , sex , bmi , fasting glucose , and insulin levels , homa - ir . they had statistically different tsh , ft4 , ft3 , and tgab levels ( table 1 ) . simple linear regression analysis revealed that visfatin serum concentration was significantly associated with autoimmunity (  = 0.1014 ; p = 0.003 ) , ft4 (  = 0.05412 ; p = 0.048 ) , ft3 (  = 0.05242 ; p = 0.038 ) , and tpoab (  = 0.0002 ; p = 0.0025 ) ( figure 2 ) . there was no association between visfatin and age , sex , bmi , tsh , tgab , fasting insulin and glucose levels , and homa - ir ( table 2 ) . in the stepwise multiple regression analysis we confirmed the association between serum visfatin level and autoimmunity ( coefficient = 3.8461 ; p = 0.0001 ) , and ft3 ( coefficient = 0.4198 ; p = 0.0441 ) , whereas age , bmi , and homa - ir did not contribute significantly . in separate stepwise multiple regression analysis we confirmed the association of serum visfatin concentration with autoimmunity ( coefficient = 4.1105 ; p = 0.0001 ) and ft4 ( coefficient = 0.1397 ; p = 0.038 ) , whereas age , bmi , and homa - ir did not enter the model . similarly , association of visfatin with tpoab ( coefficient = 0.0057 ; p = 0.0163 ) was observed with adjustment for age , bmi , ft3 , and homa - ir in multivariate regression analysis . to date , visfatin serum concentration in hypothyroidism has been analyzed in a few studies . reported elevated level of this adipocytokine in hypothyroidism with further increase after restoration of thyroid function . ozkaya et al . observed that visfatin level decreased after recovery . in those articles the etiology of hypothyroidism varied from chronic autoimmune thyroiditis , postpartum thyroiditis to thyroid function insufficiency after radioiodine treatment or after thyroidectomy . hence , to date autoimmune status of studied patients has not been taken into consideration . we hypothesized that these controversial findings might result from heterogeneity of study groups . to answer the question , whether coexisting autoimmune inflammation influences visfatin level in hypothyroid patients , we analyzed its serum concentration in chronic autoimmune thyroiditis and thyroidectomized patients negative for thyroid antibodies . since we have previously proved that visfatin mrna expression is increased in thyroid malignancies and is correlated with tumor stage , we recruited only those patients who did not have any features of active neoplastic disease . we also recruited the control group adjusted for age , sex , and bmi . to the best of our knowledge , this is the first study addressing the changes in the release of visfatin in thyroid autoimmunity . we came to interesting results indicating that visfatin serum concentration in hypothyroid patients is associated with both autoimmunity and free thyroid hormones level ( ft4 , ft3 ) . visfatin has been recognized as a cytokine with a broad range of immune and inflammatory activities , including induction of inflammatory cytokines , and regulation of macrophage and lymphocyte proliferation . visfatin stimulates the production of proinflammatory cytokines ( il-6 , tnf- , and il-1 ) and potentially acts as a chemotactic factor for monocytes . furthermore , its expression is upregulated by il-6 , tnf- , and il-1 [ 1012 ] . enhanced mrna expression of visfatin was observed in inflamed mucosa of patients with inflammatory bowel disease ( ibd ) . further analysis identified that antigen presenting cells ( i.e. , macrophages , dendritic cells ) might be a main source of this protein in ibd . visfatin has also potency for activation of t cells by upregulation of costimulatory molecules ( cd40 , cd54 , and cd80 ) on monocytes . we observed the positive association between visfatin and tpoab , and the latter is considered the best serological marker of chronic autoimmune thyroiditis . furthermore , tpoab contribute to thyroid destruction through antibody- and complement - dependent cell - cytotoxicity [ 13 , 14 ] . the first mechanism is associated with mononuclear cell infiltration of thyroid stroma . in addition , th1-derived cytokines ( il-2 , tnf- , and inf ) were found to be elevated in patients with chronic autoimmune thyroiditis . also , il-1 and tnf- have been recently reported to discriminate chronic autoimmune hypothyroid children from healthy controls . altogether , association of visfatin with tpoab observed in our study further supports our hypothesis that visfatin might be involved in the pathogenesis of chronic autoimmune thyroiditis . our findings about the association of visfatin with ft3 levels are in accordance with the results of in vitro and in vivo studies . however , controversial results whether t3 stimulates or downregulates the production of visfatin were found . in contrast , caixs et al . did not find any relationship between visfatin and free thyroid hormones . in vitro experiment showed the nonlinear regulation of visfatin mrna expression in the 3t3-l1 cell culture model affected by t3 . since our study groups significantly differed with free thyroid hormones levels , we were able to analyze visfatin concentration in a broad spectrum of ft3 and ft4 . therefore , we might suggest that pattern of visfatin changes varies in different ft3 concentration . according to our observations , as well as other authors , visfatin did not reflect insulin resistance assessed by homa - ir [ 18 , 19 ] . our study might then prove that visfatin in hypothyroidism depends on thyroid hormones level and coexisting autoimmunity . we may assume that these two factors should be taken into consideration to assess visfatin level in patients with thyroid dysfunction . in addition , the possible involvement of visfatin in pathogenesis of chronic autoimmune thyroiditis needs further research . the main limitation of our study is its cross - sectional design that does not enable us to reveal the causal pathways of relationship between visfatin and autoimmune thyroiditis . however , we used very strict criteria of exclusion to limit the possible influence of other known factors such as diabetes mellitus , other autoimmune processes , infection , and active neoplastic disease . our nonautoimmune group with hypothyroidism had been thyroidectomized at least 5 years earlier and did not have any clinical nor laboratory features of active thyroid cancer .
we hypothesized that regulation of visfatin in hypothyroidism might be altered by coexisting chronic autoimmune thyroiditis . 
 this is a prospective case - control study of 118 subjects . the autoimmune study group ( ait ) consisted of 39 patients newly diagnosed with hypothyroidism in a course of chronic autoimmune thyroiditis . 
 the nonautoimmune study group ( tt ) consisted of 40 patients thyroidectomized due to the differentiated thyroid cancer staged pt1 . 
 the control group comprised 39 healthy volunteers adjusted for age , sex , and bmi with normal thyroid function and negative thyroid antibodies . 
 exclusion criteria consisted of other autoimmune diseases , active neoplastic disease , diabetes mellitus , and infection , which were reported to alter visfatin level . 
 fasting blood samples were taken for visfatin , tsh , free thyroxine ( ft4 ) , free triiodothyronine ( ft3 ) , antithyroperoxidase antibodies ( tpoab ) , antithyroglobulin antibodies ( tgab ) , glucose , and insulin levels . 
 the highest visfatin serum concentration was in ait group , and healthy controls had visfatin level higher than tt ( p = 0.0001 ) . 
 simple linear regression analysis revealed that visfatin serum concentration was significantly associated with autoimmunity (  = 0.1014 ; p = 0.003 ) , ft4 (  = 0.05412 ; p = 0.048 ) , ft3 (  = 0.05242 ; p = 0.038 ) , and tpoab (  = 0.0002 ; p = 0.0025 ) , and the relationships were further confirmed in the multivariate regression analysis .