Iron Deficiency and Red Cell Indices in Patients with Heart Failure

In a recent report, Tkaczyszyn et al.1 showed the detrimental impact of iron deficiency (ID) on long-term survival in heart failure (HF) patients was independent of decreased red cell indices (RCI). They concluded that HF patients should be routinely screened for ID irrespective of anaemia or abnormal RCI. Although the result is attractive, we have several concerns. First, serum ferritin only reflects body iron stores. Previous reports have demonstrated several confounding factors on serum ferritin, including inflammation, oxidative stress, autoimmune diseases, renal failure, catabolic situations, and malnutrition.2-4 These abnormalities might affect serum ferritin, even increasing ferritin levels to more than 1500 µg/L. Diagnosis of ID solely based on serum ferritin or transferrin saturation might estimate erroneously the prevalence of functional ID. Moreover, the above disorders in follow-up might also affect serum ferritin, or transferrin saturation. Other parameters (such as soluble transferrin receptor) might be added to ID diagnosis. Second, the mean duration of follow-up was 699 days. In follow-up duration, there were no data about erythropoietin therapy, blood transfusions, intravenous iron therapy, or co-morbidity. All of these could affect serum ferritin and transferrin saturation significantly. These data and RCI were not measured in all patients with available follow-up. This might disturb serum ferritin and survival analysis. Additionally, the study population comprised 1821 patients from five cohorts in different nations. Although RCI detection was suggested by the European Society of Cardiology HF guidelines, the use of different devices (brand or model) and measurement methods for RCI detection might also affect RCI levels and reference range greatly.5, 6 Generally, we deem that additional data should be included in the routine screening for ID in HF patients.