It is important to note the type of intravenous iron used, as it has been well-documented that certain types of iron formulations, especially those with carboxymaltose backbones can cause hypophosphatemia due to elevating intact FGF23 (63), potentially through altering FGF23 intracellular proteolysis (see below). The gene discussed is FGF23; the disease is hypophosphatemia.