FGF23 and chronic kidney disease: Another possibility is a selection effect introduced by recruiting prevalent hemodialysis patients, who have survived over many years of CKD and after initiation of dialysis, during which progressively rising FGF23 levels are strongly associated with mortality.15, 16, 17, 18, 19, 20, 21,44 This argument asserts that prevalent hemodialysis patients, particularly those with longer dialysis vintage, are a selected population who are less susceptible to the detrimental effects of FGF23 or correlated biological processes, either intrinsically or extrinsically.