FGF23 and kidney disorder: The discovery of fibroblast growth factor 23 (FGF23), a bone-derived hormone that regulates systemic phosphate homeostasis and vitamin D metabolism via FGF-receptor 1 (FGFr1)/cofactor Klotho, which is included in a previously unrecognized hormonal bone-parathyroid-kidney axis [3], has uncovered new implications for skeletal fragility, renal disease-associated morbidity, and even cardiovascular pathology [4].