FGF23 and hypophosphatemia: The relationship between FGF23 and the pathophysiology of diseases of inherited hypophosphatemia has since been well-studied by comparing phenotypes of patients with FGF23-high and FGF23-normal hypophosphatemias (Table 1) to animal models (Table 2), healthy controls, and cases where FGF23 levels have been lowered, including blocking and knock-out experiments.