This CPB has been revised to define adequate iron stores as a serum transferrin saturation [TSAT] level greater than or equal to 20% within the prior 3 months. This definition is included in the note for requirements prior to initiating or continuing erythropoiesis stimulating agents (Aranesp, Epogen, Procrit, Retacrit, or Mircera). The background, appendix and references have been updated with additional information.