FGF23 and Iron deficiency anemia: Because fibroblast growth factor 23 (FGF23), and potentially the processes regulating its expression and cleavage, could be involved in associations of iron deficiency with outcomes, we also adjusted for total FGF23 (model 3) and intact FGF23 (iFGF23, model 4) to assess to which extent the adjustment affected the hazard ratio (HR) for all-cause and cause-specific mortality.