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

Abstract

1. Melissa Kaori Silva Litao, MD* 2. Deepak Kamat, MD, PhD† 1. *Department of Pediatrics, De La Salle Health Sciences Institute College of Medicine, Cavite, Philippines 2. †Children’s Hospital of Michigan, Wayne State University School of Medicine, Detroit, MI * Abbreviations: BNP: : brain natriuretic peptide CBC: : complete blood cell COPD: : chronic obstructive pulmonary disease CRP: : C-reactive protein ESR: : erythrocyte sedimentation rate FMF: : familial Mediterranean fever MCV: : mean cell volume RBC: : red blood cell RDW: : red blood cell distribution width 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)(7)(8) a predictor of all-cause mortality, (9)(10) and a prognostic tool for morbidity and mortality associated with sepsis and cardiovascular disease. (4)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) This article focuses on discussing the RDW as a diagnostic and prognostic tool in various medical conditions. ### What Is the RDW? Each RBC is shaped as a biconcave disk with a depressed center, its volume ranging from 80 to 100 femtoliters (fL; 1 fL = 10-15 L) in adults (represented by the MCV in the CBC count). The RBC membrane is extremely flexible and, in certain conditions, is able to change shape …