FGF23 and nutritional disorder: The pro-inflammatory cytokines tumour necrosis factor alpha (TNFα) and interleukin 6 (IL6) and iron deficiency have been shown to increase osteocytic FGF23 transcription and cleavage, resulting in increased plasma concentrations of particularly c-terminal FGF23 (cFGF23) and to a lesser extent intact FGF23 (iFGF23) [4, 5].