Endocrine Abstracts

Subclinical hyperthyroidism (SH) is characterised by supressed serum TSH concentration accompanied by fT3 and fT4 levels maintained within their reference ranges. The vascular endothelium as a specific target of thyroid hormones is strongly affected in hyperthyroidism. We aimed to compare the alterations of the endothelial function, haemostatic and inflammatory parameters in patients with SH in comparison with overt hyperthyroidism (OH) due to Graves’ disease and toxic nodular goiter. In the present study, we determined serum levels of soluble forms of ICAM-1, VCAM-1, vWF, IL-6, IL-12, IL-18 and CRP to elucidate a possible role of those parameters as markers of endothelium dysfunction (ED). 117 patients were included into the study: 56 patient with OH, 61 with SH and 39 euthyrotic controls (CG). In our study fibrinogen, vWF, PAI-1 and VCAM-1 levels increased significantly in study groups compared with the CG. We also found an increase in serum CRP, IL-6, IL-12 and IL-18 levels in OH and SH groups. In SH group we observed the highest levels of serum CRP and IL-6. Similar values for sICAM-1, E-selectin were demonstrated in study and CG. These results may reflect a relative hypercoagulability state both in subjects with SH and OH. In summary, our results suggest that hyperthyroidism is accompanied by the endothelial damage, which depends both on the cause of thyrotoxicosis and on degree of hyperthyroidism. Elevated concentrations of the markers of the endothelial damage may serve as a confirmation that persons with hyperthyroidism are extremely predisposed to the occurrence of the cardiovascular diseases.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector