KL and chronic kidney disease: Inflammation (a); OS (b); the CKD-MBD including low vitamin D, hyperphosphatemia, high fibroblast growth factor 23 (FGF23), and low Klotho; (c) and the accumulation of endogenous inhibitors on NO synthase, which will be described in a separate section (see below and Figure 2), are the main risk factors underlying this systemic disorder in CKD patients.