The relation between visfatin/Nampt levels and endothelial function in CKD is not merely descriptive, but may also have a functional impact, since visfatin/Nampt levels negatively correlate with endothelial function estimated as flow-mediated dilation (FMD) in brachial artery or glomerular filtration rate (GFR) [41, 42]. This evidence concerns the gene NAMPT and chronic kidney disease.