KL and atherosclerosis: We next investigated the association between the serum Klotho level and various markers of vascular dysfunction, including flow-mediated dilatation (FMD), a marker of nitric oxide-dependent endothelial function, brachial-ankle pulse wave velocity (baPWV), a marker of arterial stiffness, maximum intima-media thickness (max IMT), a marker of atherosclerosis, and the abdominal aortic calcification index (ACI), a marker of vascular calcification (Figure 2).