However, the KAINOS intact assay has a reference range (10–50 pg/mL), and Endo et al. proposed that its measurement of serum FGF23 levels >30 pg/mL should typically be used as a diagnostic criterion for the presence of disease caused by excess FGF23 action, such as FGF23-dependent hypophosphatemia, irrespective of medical treatment [23]. Here, FGF23 is linked to hypophosphatemia.