In three independent cardiac surgery cohorts, patients with AKI have higher levels of C-terminal FGF23 (cFGF23) than those who did not develop AKI as early as cardiopulmonary bypass ending.377,378,382 The predictive performance of cFGF23 was higher than other urinary injury biomarkers, including NAG (n-acetyl-b-(d)-glucosaminidase), KIM-1 (kidney injury molecule-1), and NGAL (neutrophil gelatinase-associated lipocalin) at the end of cardiopulmonary bypass.377 FGF23 is also thought to be a candidate prognostic marker for the adverse outcomes in AKI patients. This evidence concerns the gene FGF23 and acute kidney injury.