Evaluation of Endothelial Function in Subclinical Thyroid Dysfunction

We read with interest the article on the evaluation of function in subclinical hypothyroidism (SH) subclinical hyperthyroidism (SHr) by Cikim et al. (1). the authors state, SH may have adverse effects on endothelial independent from other well-known risk factors such as dyslipidemia. Indeed, association of SH with changes in serum lipoprotein and the effect of Levothyroxine replacement therapy these changes are still open questions (2–4). We agree with the authors that endothelial dysfunction, condition characterized by decreased nitric oxide availability, a pivotal role in the pathogenesis of coronary disease (5). However, the authors state that impairment has not been clearly demonstrated mild thyroid dysfunction. We had previously a reversible alteration of endothelium dependent and reduced nitric oxide availability SH patients (6). The study population included 14 SH patients and 28 euthyroid controls, matched to the group for sex, age and body mass index and divided, to the lipid profile, into a normocholesterolemic (n 14) and a slightly hypercholesterolemic (n 14, matched to SH patients). Our results indicated the endothelial impairment of SH patients cannot accounted for exclusively by the concomitant mild hypercholesterolemia since endothelium dependent vasodilation significantly reduced in comparison to both control groups. Therefore, besides serum lipid alterations, suggested a direct effect of thyroid hormone in endothelial dysfunction development of SH .