Back to Basics: Red Blood Cell Distribution Width: Clinical Use beyond Hematology

The complete blood cell (CBC) count is a widely available and commonly used inexpensive laboratory test used in clinical practice. Information contained therein includes the white blood cell count and differential count, red blood cell (RBC) count, RBC indices, hemoglobin level, hematocrit concentration, and platelet count. The RBC indices include the mean cell volume (MCV), mean cell hemoglobin, mean cell hemoglobin concentration, and RBC distribution width (RDW). (1) Traditionally, the clinical use of RDW has been limited to helping differentiate certain types of anemias (eg, β-thalassemia minor and iron deficiency anemia, which can both have decreased MCV and decreased mean cell hemoglobin but will differ in their RDW). (2) During the past decade, this quick and inexpensive test has been the subject of several studies attempting to evaluate its use as, among other things, an inflammatory marker, (3)(4)(5)(6)(...