Department of Nephrology, Gülhane School of Medicine, Ankara, Turkey.
Am J Nephrol. 2011;33(1):25-32. doi: 10.1159/000322581. Epub 2010 Dec 9.
BACKGROUND/AIMS: Subclinical or frank hypothyroidism is causally implicated in endothelial dysfunction. Since the plasma concentration of the active form of thyroid hormone, triiodothyronine (T₃), is reduced in chronic kidney disease (CKD), where endothelial function is frequently altered, low T₃ may be a factor implicated in this disturbance in CKD patients.
We investigated the relationship between flow-mediated vasodilatation (FMD) and thyroid hormones in a series of 217 nondiabetic patients with stage 3-4 CKD.
The plasma concentration of free T₃ (fT₃) was closely associated with FMD (r = 0.38; p < 0.001). fT₃ was also inversely associated with hemoglobin (r = -0.41; p < 0.001), systolic pressure (r = -0.28; p < 0.001) and the plasma concentration of the endogenous inhibitor of NO synthase, asymmetric dimethylarginine (ADMA; r = -0.18; p = 0.007). However, adjustment for ADMA markedly attenuated the fT₃-FMD link, a phenomenon suggesting that raised plasma ADMA, possibly driven by low fT₃, at least in part mediates the adverse effects of low T₃ on endothelial function in CKD.
Low T₃ in patients with moderate-to-severe CKD is a marker of endothelial dysfunction. This study sets a solid rationale for designing specific intervention studies aimed at clarifying the nature (causal or not causal) of the endothelial function-T₃ link in CKD.
背景/目的：亚临床或显性甲状腺功能减退症与血管内皮功能障碍有因果关系。由于活性甲状腺激素三碘甲状腺原氨酸（T₃）的血浆浓度在慢性肾脏病（CKD）中降低，而内皮功能在 CKD 中经常改变，因此低 T₃可能是导致 CKD 患者发生这种功能障碍的一个因素。
我们在一系列 217 例非糖尿病 3-4 期 CKD 患者中研究了血流介导的血管舒张（FMD）与甲状腺激素之间的关系。
游离 T₃（fT₃）的血浆浓度与 FMD 密切相关（r = 0.38；p < 0.001）。fT₃ 也与血红蛋白（r = -0.41；p < 0.001）、收缩压（r = -0.28；p < 0.001）和内源性一氧化氮合酶抑制剂不对称二甲基精氨酸（ADMA）的血浆浓度呈负相关（r = -0.18；p = 0.007）。然而，调整 ADMA 后，fT₃-FMD 之间的联系明显减弱，这表明升高的血浆 ADMA，可能是由低 fT₃引起的，至少部分介导了低 T₃对 CKD 内皮功能的不良影响。
中重度 CKD 患者的低 T₃是血管内皮功能障碍的一个标志物。本研究为设计旨在阐明 CKD 中内皮功能与 T₃之间关系的本质（因果关系或非因果关系）的特定干预研究提供了坚实的依据。
