FGF23 and chronic kidney disease: Since FGF23 also exerts pro-inflammatory effects,30,63 and strong correlations are observed in CKD between FGF23 and inflammatory markers,33 this represents a feed-forward loop, in which the effects of inflammation and FGF23 are fueling one another (Fig. 6i), offering one possible explanation for the maladaptive and exponential increases in FGF23 levels that occur in advanced CKD.