FGF23 and nephrolithiasis: Reduced inhibition of 1,25(OH)2D synthesis by FGF-23 [37] could potentially be responsible for the elevation in serum 1,25(OH)2D concentrations, despite identical FGF-23 concentrations in stone-formers, since the expected significant inverse correlation between FGF-23 and 1,25(OH)2D3 observed in control subjects (P<0.001) was not observed in Ca kidney stone-formers (P = 0.16).