In 1997, the workgroup for the NKF-DOQI clinical practice guidelines for treating anemia in chronic renal failure (National Kidney Foundation Dialysis Outcomes Quality Initiative [NKF-DOQI], 1997) recommended hematocrit levels of 33–36% corresponding to a target Hb level of 11–12 g/dL, which was higher than the target of 30–33% set by the FDA in 1989; in 1994, the FDA increased the target hematocrit level range to 30–36% (Ma et al., 1999). This evidence concerns the gene GSTM1 and anemia (phenotype).