Abnormal erythrocyte morphology Increased RBC distribution width 2018-07-07T14:42:53Z Increased red blood cell distribution width Red blood cell distribution width (RDW) is a simple parameter of the standard full blood count and a measure of heterogeneity in the size of circulating erythrocytes. It is provided by automated hematology analyzers and it reflects the range of the red cell size. It is calculated by dividing the standard deviation of erythrocyte volume by the mean corpuscular volume (MCV) and multiplied by 100 to convert to a percentage. Although RDW has been traditionally used in the investigation of the etiology of anemia there is an increasing evidence linking elevated RDW with poor outcome in general population [4, 5], in patients with coronary artery disease, with metabolic syndrome and heart failure.