GSTM1 and anemia: ,12,16,18-24 This varying prevalence of PTA probably is observed because different criteria have been suggested for the definition of anemia, including Hb < 13 g/dl for male patients and < 12 g/dl for females;16 Hb < 13.5 g/dl for males and < 12 g/dl for females (K/DOQI);25 Hb < 12 g/dl for males and < 11 g/dl for females (European Best Practice Guidelines);26 Hb < 12.5 for males and < 11.5 g/dl for females;18 Hb < 11 after three months;19 and hematocrit (Hct) < 33%.8