FGF23 and hypophosphatemia: In diseases of FGF23 over production where renal function is maintained, such as X‐linked hypophosphatemia (XLH) and autosomal dominant hypophosphatemic rickets (ADHR), high levels of FGF23 reduce 1,25D production and cause hypophosphatemia, impaired growth, rickets, and osteomalacia (Farrow et al., 2011; Ganz et al., 2019; Martin et al., 2012).