HIF1A and nutritional disorder: These include iron deficiency only in situations of impaired FGF23 cleavage,(33) systemic inflammation via a direct effect on osteocytes and indirectly mainly by regulating iron metabolism or by altering systemic calcium, phosphate, and vitamin D metabolism,(34) and finally hypoxia‐inducible factor (HIF)‐1α, which is induced in osteocytes and osteoblasts in response to iron deficiency or hypoxia.(35) The degradation of 1,25(OH)2D occurs in the kidneys by CYP24A1, which is stimulated by 1,25(OH)2D3 and FGF23,(36) while inhibited by PTH.