Markers of endothelial dysfunction in patients with iodine induced hyperthyroidism

INTRODUCTION: It has been reported that hyperthyroidism is associated with an altered endothelial function and increased risk of arterial thromboembolism. The aim of our study was to estimate chosen markers of endothelial dysfunction in iodine-induced thyrotoxicosis (IIT). MATERIALS AND METHODS: The groups studied consisted of 41 hyperthyroid subjects, who had been treated with amiodarone (n = 6) or vitamin preparations supplemented with iodine (n = 35) and 40 persons with normal thyroid function. The following parameters were measured: thyroglobulin antibodies (TG Ab), thyroid peroxidase antibodies (TPO Ab), THS receptor antibodies (TR Ab), soluble adhesion molecules: sVCAM-1 and sICAM-1, von Willebrand factor (vWF), plasminogen activator inhibitor-1 (PAI-1), C-reactive protein (CRP), fibrinogen and urine iodine concentration. RESULTS: Patients with IIT had significantly higher levels of sVCAM-1 (p < 0.01), IL-6 (p < 0.005), fibrinogen (p < 0.005) and CRP (p < 0.05) in comparison to healthy subjects, whereas sICAM-1, PAI-1 and vWF concentrations did not differ between the groups studied. The highest sVCAM-1 levels were observed in patients with amiodarone induced thyrotoxicosis, and fibrinogen and CRP--in subjects receiving vitamin preparations. There were significant correlations between sVCAM-1 concentration and the levels of sICAM-1 (r = 0.341; p = 0.029) and PAI-1 (r = 0.347; p = 0.026), as well as with urine iodine concentration (r = 0.448; p = 0.004). IL-6 concentration correlated with vWF (r = 0.456; p = 0.003), TPO Ab (r = 0.328; p = 0.036) and PAI-1 level (r = 0.319; p = 0.042). CONCLUSION: Iodine induced thyrotoxicosis is associated with an increase of sVCAM-1 and IL-6 levels, possibly reflecting inflammatory and destructive processes in the thyroid gland. However, increased procoagulant activity was not found in patients with IIT.