Erythropoietin and iron: separating the builder from his blocks

  • Sandaruwani AbeysiriEmail author
  • Marisa Chau
  • Toby Richards

To the Editor,

We read with interest the recently published systematic review on safety and efficacy of erythropoietin and iron therapy in surgical patients.1 Nevertheless, we question as to whether the authors are correct to place these two interventions together.

Erythropoietin is a hormone for erythropoiesis—i.e., it is the builder of red blood cells. On the other hand, iron is a substrate for haemoglobin—i.e., it is a building block. In combination, intravenous iron increases the effectiveness of erythropoiesis-stimulating agents (ESAs)2—i.e., the builder supplied with sufficient building blocks can then work effectively. Conversely, ESAs do not work if the underlying problem is iron deficiency,3 and giving intravenous iron alone does not lead to polycythemia.4

In the meta-analysis by Kei et al.,1 there is no mention of the patient iron status. Furthermore, non-anemic populations were also included, where we can infer that the majority (> 75%) of the study populations may be iron replete.5 Therefore, intravenous iron has no role in these patients and would not be expected to change the primary endpoint reported in the meta-analysis. The analysis may therefore be confounded.

The interpretation of these data would be enhanced by knowing what were the outcomes and analyses for those patients for whom iron therapy was actually clinically indicated.


Conflicts of interest

None declared.

Editorial responsibility

This submission was handled by Dr. Hilary P. Grocott, Editor-in-Chief, Canadian Journal of Anesthesia.


  1. 1.
    Kei T, Mistry N, Curley G, et al. Efficacy and safety of erythropoietin and iron therapy to reduce red blood cell transfusion in surgical patients: a systematic review and meta-analysis. Can J Anesth 2019; 66: 716-31.CrossRefPubMedPubMedCentralGoogle Scholar
  2. 2.
    Roger SD. Practical considerations for iron therapy in the management of anaemia in patients with chronic kidney disease. Clin Kidney J 2017; DOI: Scholar
  3. 3.
    Karlsson T. Effects of iron supplementation on erythropoietic response in patients with cancer-associated anemia treated by means of erythropoietic stimulating agents. ISRN Hematol 2011; DOI: Scholar
  4. 4.
    Clevenger B, Richards T. Pre-operative anaemia. Anaesthesia 2015; DOI: Scholar
  5. 5.
    Wu YG, Zeng Y, Shen B, et al. Combination of erythropoietin and tranexamic acid in bilateral simultaneous total hip arthroplasty: a randomised, controlled trial. HIP Int 2016; DOI: Scholar

Copyright information

© Canadian Anesthesiologists' Society 2019

Authors and Affiliations

  1. 1.University College LondonLondonUK
  2. 2.University of Western AustraliaPerthAustralia

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