Nutritional iron deficiency in patients with chronic illnesses

The Review by Michael Zimmermann and Richard Hurrell on nutritional iron deficiency (Aug 11, p 511)1Zimmermann MB Hurrell RF Nutritional iron deficiency.Lancet. 2007; 370: 511-520Summary Full Text Full Text PDF PubMed Scopus (849) Google Scholar was timely and comprehensive, but we believe several issues need clarification. In table 2, Zimmermann and Hurrell define adult ferritin concentrations of less than 30 μg/L as defining iron deficiency; this value is similar to what WHO recommends when diagnosing absolute iron deficiency. When taking care of patients with chronic illness and associated inflammation, however, this approach seems too narrow. Research has revealed that well above 50% of patients with chronic heart failure have iron deficiency (as assessed by the gold standard of bone-marrow biopsy), but with mean ferritin concentrations of 75 μg/L.2Nanas JN Matsouka C Karageorgopoulos D et al.Etiology of anemia in patients with advanced heart failure.J Am Coll Cardiol. 2006; 48: 2485-2489Summary Full Text Full Text PDF PubMed Scopus (311) Google Scholar And the UK guidelines on anaemia management in chronic kidney disease3National Collaborating Centre for Chronic ConditionsAnaemia management in chronic kidney disease: national clinical guideline for management in adults and children. Royal College of Physicians, London2006Google Scholar recommend that a ferritin concentration of less than 200 μg/L should trigger initiation of treatment with intravenous iron. These cut-offs define patients with functional iron deficiency. Zimmermann and Hurrell also suggest that serum transferrin receptor (sTfR) and erythrocyte zinc protoporphyrin (ZPP) should be used for assessing iron status, although they admit that the “sensitivity and specificity of sTfR and ZPP are low” and that the application of sTfR is “limited by high costs…and lack of an international standard”. We conclude that it seems premature to include ZPP and sTfR in routine clinical testing. More research is needed to validate appropriate cut-offs for iron deficiency and it is important to include the distinction between absolute and functional iron deficiency in our educational efforts. We declare that we have no conflict of interest.