Chang et al. [45] evaluated the relationship between FGF23 and adverse outcomes in 149 patients with CKD superimposed with AKI requiring kidney replacement therapy (KRT); their results showed that higher plasma cFGF23 levels were associated with a high risk for 90-day mortality [hazard ratio (HR) 2.5; P < 0.001] even after adjustment for sex, age, baseline eGFR, and disease severity. Here, FGF23 is linked to acute kidney injury.