In the analysis, baseline Hb level ≤ 10 mg/dL (OR, 20.1; 95% CI, 4.71–125, p < 0.001), Ca level < 9.5 mg/dL (OR, 4.28; 95% CI, 1.25–15.2, p = 0.009), and transferrin saturation (TSAT) < 25% (OR, 12.8; 95% CI, 2.51–129, p < 0.001) were associated with anemia improvement (Table 2). This evidence concerns the gene GSTM1 and anemia (phenotype).