Alarmingly, the fact that cFGF23 does not necessarily reflect iFGF23 concentrations is not incorporated in commonly applied diagnostic algorithms of hypophosphatemia.(6) In the Netherlands and also in other countries, hospitals only use cFGF23 assays and not iFGF23 assays, even though Hartley and colleagues found that measurement of iFGF23 is superior to cFGF23 in making a diagnosis of FGF23‐mediated hypophosphatemia.(16, 17, 18). The gene discussed is FGF23; the disease is hypophosphatemia.