GSTM1 and anemia: Although 11.5 % of the lowest tertile of Hb and 24.6 % of the middle tertile of Hb in patients with severe IFTA showed preserved eGFR (≥ 60 mL/min/1.73 m2) in the present study, one previous study demonstrated that low erythropoietin levels predicted rapid eGFR decline in type 2 diabetic patients with anemia [26].