FGF23 and PTH--double agents at the heart of CKD

The changes in mineral metabolism in chronic kidney disease (CKD) are well established as being major contributors to the morbidity and mortality of CKD patients, both early and established. The known factors involved were considered to be phosphate (P), calcium, parathyroid hormone (PTH), vitamin D and metabolic acidosis. A number of epidemiological studies have shown that high P associates with mortality; but more recently, the field has been invigorated by a new player, namely fibroblast growth factor 23 (FGF23). We shall review the exciting developments in research on FGF23 and its interplay with other factors that are known to be altered in CKD, particularly P and calcium, PTH and vitamin D. In particular, we will consider new findings on the effect of FGF23 on the heart.