Fibroblast growth factor-23 (FGF23), a phosphate-regulating hormone that rises in early CKD, has been causally linked to left ventricular hypertrophy (LVH) via FGFR4 signaling independent of Klotho, as shown in murine models and corroborated in human studies associating elevated FGF23 with increased LVH and mortality [213,214,215]. This evidence concerns the gene KL and chronic kidney disease.