FGF23 and chronic kidney disease: Klotho-depletedmice, characterized by an excessive concentration of calcitriol, hypercalcemia andhyperphosphatemia, suffer from hyperaldosteronism.5 Patients with CKD also present with heightened levels ofaldosterone,6 severe klotho deficiency,resistance to the action of fibroblast growth factor 23 (FGF-23) and vasculardamage.