For example, both Thomas et al. and Fishbane et al. defined functional iron deficiency as CHr <28pg [12, 21],and reported that a CHr cut off level of <28pg predicted IDA better than serum ferritin and transferrin saturation among a cohort of dialysis patients on erythropoietin therapy[12, 21]. The gene discussed is EPO; the disease is Iron deficiency anemia.