FGF23 and chronic kidney disease: One of the first to report the association between FGF23 levels and high mortality was Orlando-Gutiérrez, who observed among patients with stage 5 CKD on dialysis grouped into four quartiles according to their FGF23 levels that the higher the FGF23 level, the higher the mortality rate [50], this same association was reported in the chronic renal insufficiency cohort (CRIC) and HOST studies conducted in patients who had some degree of CKD but had not yet started dialysis [51, 52].