Alternatively, FGF23 may promote myocardial fibrosis and remodelling via activation of the renin–angiotensin–aldosterone system27 and may contribute to the development of anaemia28; we did observe a relatively strong inverse association between FGF23 and haemoglobin and treatment of iron deficiency in HF is known to result in reduction in FGF23 levels.29 This evidence concerns the gene REN and Iron deficiency anemia.