Flow-mediated vasodilatation of the brachial artery (FMD)and reactive hyperemia index (RHI) measured by peripheral arterial tonometry have been used as the assessment of endothelial function in clinical settings.Several studies have reported that both markers to reflect pathophysiological abnormalities related with early stages of atherosclerosis and also to predict future cardiovascular events.Even so, they are known to be weakly associated with each other, however, the mechanisms underlying this weak association remain to be fully clarified.