title: Determinants of red cell distribution width (RDW) in cardiorenal patients: RDW is not related to erythropoietin resistance.
abstract: BACKGROUND
  Studies have shown that red cell distribution width (RDW) is related to outcome in chronic heart failure (CHF). The pathophysiological process is unknown. We studied the relationship between RDW and erythropoietin (EPO) resistance, and related factors such as erythropoietic activity, functional iron availability and hepcidin.
  
  
  RESULTS
  In the Mechanisms of Erythropoietin Action in the Cardiorenal Syndrome (EPOCARES) study, which investigates the role of EPO in 54 iron-supplemented anemic patients with CHF and chronic kidney disease (CKD) (n = 35 treated with 50 IU/kg/wk Epopoetin beta, n = 19 control), RDW was not associated with EPO resistance. We defined EPO resistance by EPO levels (r = 0.12, P = .42), the observed/predicted log EPO ratio (r = 0.12, P = .42), the increase in reticulocytes after 2 weeks of EPO treatment (r = -0.18, P = .31), and the increase of hemoglobin after 6 months of EPO treatment (r = 0.26, P = .35). However, RDW was negatively correlated with functional iron availability (reticulocyte hemoglobin content, r = -0.48, P < .001, and transferrin saturation, r = -0.39, P = .005) and positively with erythropoietic activity (soluble transferrin receptor, r = 0.48, P < .001, immature reticulocyte fraction, r = 0.36, P = .01) and positively with interleukin-6 (r = 0.48, P < .001). No correlation existed between hepcidin-25 and RDW.
  
  
  CONCLUSIONS
  EPO resistance was not associated with RDW. RDW was associated with functional iron availability, erythropoietic activity, and interleukin-6 in anemic patients with CHF and CKD.
authors.affiliation: Department of Cardiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Mireille E
authors.initials: ME
authors.lastname: Emans
authors.forename: Karien
authors.initials: K
authors.lastname: van der Putten
authors.forename: Karlijn L
authors.initials: KL
authors.lastname: van Rooijen
authors.forename: Rob J
authors.initials: RJ
authors.lastname: Kraaijenhagen
authors.forename: Dorine
authors.initials: D
authors.lastname: Swinkels
authors.forename: Wouter W
authors.initials: WW
authors.lastname: van Solinge
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Cramer
authors.forename: Pieter A F M
authors.initials: PA
authors.lastname: Doevendans
authors.forename: Branko
authors.initials: B
authors.lastname: Braam
authors.forename: Carlo A J M
authors.initials: CA
authors.lastname: Gaillard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000097:blood / Q000188:drug therapy / Q000473:pathology; D048429:Cell Size / Q000187:drug effects; D004351:Drug Resistance / Q000187:drug effects / Q000502:physiology*; D004909:Erythrocyte Indices / Q000187:drug effects / Q000502:physiology*; D004912:Erythrocytes / Q000187:drug effects / Q000473:pathology*; D004921:Erythropoietin / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D008297:Male; D011446:Prospective Studies
chemical_list: D004921:Erythropoietin