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Particularities of endothelial dysfunction in hypothyroid patients.

BACKGROUND
It is well known that hypothyroidism promotes the premature onset of subclinical atherosclerosis. This condition is defined by endothelial dysfunction (ED) and increased arterial stiffness (AS) and leads to augmentation of peripheral vascular resistance.


AIM
To assess the presence and severity of ED and to follow its evolution under therapy in three groups of hypothyroid patients, we used three different noninvasive methods: carotidian intima-media thickness (IMT), flow mediated vasodilatation (FMD), and AS.


METHODS
The study group consisted of 56 young, hypothyroid women without associated cardiovascular pathology or risk factors for atherosclerosis. We selected our patients in order to have normal IMT (< 0.9 mm) and assessed the basal diameter of the brachial artery and the alterations of FMD and of AS parameters: pulse wave velocity (PWV) and augmentation index (AIx).


RESULTS
We found, in all patients, a reduced basal diameter of brachial artery, pathological patterns of FMD, and increased values of PWV and AIx, compared to controls, in relation with the severity of thyroid dysfunction. We documented an improvement of ED after therapy with L-thyroxin.


CONCLUSIONS
ED, documented in hypothyroid patients by means of three noninvasively methods, was strongly related to the severity of thyroid disease. We detected, in all three subgroups, significant alterations of FMD and AS, even in the absence of structural changes, documented by a normal IMT. ED improved consistently after restoring the euthyroid state.