GSTM1 and renal dialysis: Figure 2a and 2b compare the SD-Hb seen in ESA treated Peritoneal Dialysis patients with population normals obtained from the Scripps-Kaiser database (Fig. 2a), and NHANESIII (Fig. 2b). Hb-var in the ESA naïve group was similar in magnitude and trend as observed in the NHANESIII and Scripps-Kaiser populations (Fig. 3).