A recent multicenter retrospective cohort study even demonstrated that non-dialysis-dependent CKD patients without anemia but with transferrin saturation (TSAT) levels ≤ 20% experienced a 2.21-fold increase in all-cause mortality risk (adjusted hazard ratio [aHR]: 2.21; 95% confidence interval [CI]: 1.36–3.57; p = 0.001) and a 1.66-fold increase in CKD progression compared to those with TSAT levels >20% [9]. Here, TF is linked to anemia (phenotype).