Red Cell Distribution Width as a Biomarker for Heart Failure: Still Not Ready for Prime-Time

We would like to thank García-Escobar and Ingelmo for their letter regarding our article on the use of biomarkers in routine clinical care for heart failure.1,2 It was with interest that we read their comments on the use of red cell volume distribution width (RDW) as another biomarker for use in the management of patients with heart failure. As mentioned in their letter, RDW is a measure of heterogeneity of red blood cell (RBC) volume or anisocytosis and not a measure of RBC size or volume itself.3 RDW is a number generated by automated blood count machines. Increased variations in RBC volume – that is, a high RDW, is seen in anaemic states (such as iron deficiency anaemia, sickle cell anaemia, thalassaemia and megaloblastic anaemia), in patients using chemotherapeutic agents, in cardiovascular disease, thyroid disease and myelodysplastic syndromes.3