title: Evaluation of the effect of L-thyroxin therapy on endothelial functions in patients with subclinical hypothyroidism.
abstract: Subclinical hypothyroidism (SH) is characterized by normal serum free T4 (FT4), free T3 (FT3) levels and increased serum thyroid-stimulating hormone (TSH) levels. Endothelial dysfunction, which is an early step of atherosclerosis, has been reported in patients with subclinical hypothyroidism. The aim of this study is to evaluate endothelial functions and the effect of L-thyroxin (L-T4) therapy on endothelial functions in SH. Twenty-seven patients with SH and 22 healthy controls were evaluated in terms of endothelial functions, using brachial artery Doppler ultrasonography. After restorating euthyroidism, measurements were repeated. Baseline and nitroglycerin induced diameter (NID) of brachial artery were similar in patients with SH and the control group. Compared to the control group, the patients with SH showed significantly reduced flow-mediated diameter (FMD). Baseline and NID values were significantly higher after LT4 therapy in SH group. FMD also significantly increased after LT4 therapy. Hypothyroidism accelerates atherogenesis through modification of atherosclerotic risk factors and direct effects on the blood vessels. In this study, we observed marked improvement in endothelial functions after L-T4 therapy in SH patients. We suggest that thyroid hormone replacement therapy may help to prevent atherosclerosis in this group of patients.
authors.affiliation: Internal Medicine Department, Istanbul Education and Research Hospital, Istanbul, Turkey. falibaz@yahoo.com
authors.forename: Fatma
authors.initials: F
authors.lastname: Alibaz Oner
authors.forename: Selen
authors.initials: S
authors.lastname: Yurdakul
authors.forename: Ender
authors.initials: E
authors.lastname: Oner
authors.forename: Ayse
authors.initials: A
authors.lastname: Kubat Uzum
authors.forename: Mecdi
authors.initials: M
authors.lastname: Erguney
mesh_terms: D000328:Adult; D050197:Atherosclerosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D001783:Blood Flow Velocity / Q000187:drug effects; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy* / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin; D012039:Regional Blood Flow / Q000187:drug effects; D012307:Risk Factors; D012720:Severity of Illness Index; D013974:Thyroxine / Q000627:therapeutic use*; D014421:Turkey / Q000453:epidemiology; D018608:Ultrasonography, Doppler; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents; D055815:Young Adult
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin; D013974:Thyroxine