FGF23 and chronic kidney disease: Among them, interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and fibroblast growth factor 23 (FGF-23) are robust independent predictors of all-cause mortality in stage 5 CKD patients, with IL-6 also serving as a reliable classifier of clinically overt cardiovascular disease [9,10].