FGF23 and chronic kidney disease: Data from a recent metanalysis showed the estimated absolute difference in mean FGF23 concentrations between the top to bottom third of the FGF23 distributions ranged from 72 RU/mL in general population studies to 433 RU/mL in non-dialyzed CKD studies and to 8644 RU/mL in dialysis population studies (C-terminal studies only) [19].