FGF23 and Hypercalcemia: Klotho and Fgf23 null mice highlight the relation between Klotho and FGF23 by displaying similar phenotypes comprising dysfunctional FGF23 signaling, hypercalcemia, hyperphosphatemia, and increased calcitriol levels (Kuro‐o et al., 1997; Larsson et al., 2004; Shimada et al., 2004).