Figure 1 shows the flow diagram for the study. Enrolled patients were elderly (69.66 ± 5.11 years old) with a recent diagnosis of functional IDA (with Hb concentration < 13.0 g/dL in men and <12.0 g/dL in women, TSAT <20%, and ferritin level >100 μg/L) and with moderate CKD (eGFR 43.24 ± 7.30 mL/min/1.73 m2), not yet on ESA therapy. The baseline characteristics of the three groups of patients are shown in Table 1. This evidence concerns the gene GSTM1 and chronic kidney disease.