FGF23 and Iron deficiency anemia: The situation is then severely exacerbated by two other factors: (1) the core pathology of CKD, particularly inflammation and iron deficiency, which are potent vitamin D-independent drivers of FGF23 production [82,83], and (2) the use of active vitamin D analogs to treat SHPT, which are powerful stimulators of the FGF23 gene [84].