In Portale et al. study the median plasma FGF23 level was 2.4 times higher in CKD 2–4 patients than in 42 healthy children of comparable age of 12 ± 4 years (138 RU/mL vs. 57 RU/mL, respectively; according to the manufacturer 1 RU/mL is roughly 2 pg/mL). This evidence concerns the gene FGF23 and chronic kidney disease.