Plasma visfatin concentrations increase in both hyper and hypothyroid subjects after normalization of thyroid function and are not related to insulin resistance, anthropometric or inflammatory parameters.

OBJECTIVE: The objective of this study was to evaluate plasma visfatin levels in thyroid dysfunction and its relationship with inflammatory, anthropometric and insulin resistance parameters.

DESIGN AND PATIENTS: Twenty-four hyperthyroid and 27 hypothyroid patients were studied before and after treatment. Forty-five euthyroid subjects were used as control group.

MEASUREMENTS: Fasting plasma visfatin, IL-6, C reactive protein, adiponectin, thyroid hormones, waist-to-hip ratio, BMI, percentage of body fat and homeostasis model insulin resistance index (HOMA-IR) were measured.

RESULTS: Hyperthyroid patients showed increased insulin resistance, IL-6 and visfatin levels compared with controls (3.21 +/- 3.0 vs. 1.67 +/- 0.75, P = 0.022; 3.35 +/- 0.41 vs. 2.10 +/- 0.25 pg/ml, P = 0.016; and 37.4 +/- 5.81 vs. 23.79 +/- 4.2 ng/ml, P = 0.061 respectively). After normalization of thyroid function, IL-6 levels and HOMA-IR decreased (2.35 +/- 0.37 vs. 2.10 +/- 0.25 pg/ml, P = 0.045 and 3.21 +/- 0.60 vs. 2.28 +/- 0.38, P = 0.032 respectively), while body weight, adiposity and visfatin levels increased (26.1 +/- 1.2 vs. 26.7 +/- 1.2 kg/m(2), P = 0.049; 30.9 +/- 1.6 vs. 32.2 +/- 1.6%, P = 0.007; and 37.4 +/- 5.81 vs. 63.13 +/- 8.72 ng/ml, P = 0.047 respectively). C reactive protein and adiponectin levels were similar to those of the control group. Hypothyroid patients showed high visfatin levels (40.59 +/- 3.07 vs. 29.34 +/- 4.9 ng/ml, P = 0.049) that increased after treatment (81.4 +/- 9.2 ng/ml, P = 0.001) without changes in anthropometric or insulin resistance parameters. C reactive protein, IL-6 and adiponectin levels were similar to those of the control group. No correlations between visfatin and any analysed parameter were found in either hyper- or hypothyroidism.

CONCLUSION: Visfatin exhibits a marked increase after normalization of thyroid function in both hyper and hypothyroid patients. We suggest that visfatin may play a role in the hormone stabilization process independent of anthropometric, inflammatory or insulin resistance variables.