RDW is an acronym for Red Cell Distribution Width, a medical term used to describe a measure of the variation in size of red blood cells (erythrocytes) in a blood sample. It is often expressed as a percentage. The RDW value is an important component of a complete blood count (CBC) and is obtained by automated blood analyzers.
The RDW measurement provides crucial information about the uniformity in the size of red blood cells. Red blood cells typically exhibit a certain degree of size variation; however, an abnormally high or low RDW percentage can be indicative of specific underlying conditions. A higher RDW value suggests a greater range in red blood cell sizes, known as anisocytosis, which may be observed in various medical conditions, such as nutritional deficiencies (e.g., iron, vitamin B12, or folate deficiency), certain anemias (e.g., iron deficiency anemia, megaloblastic anemia), or chronic diseases.
Conversely, a lower RDW percentage, or reduced red cell distribution width, indicates a narrower range of red blood cell sizes, referred to as microcytosis. This can be observed in conditions like thalassemia, iron overload disorders (e.g., hereditary hemochromatosis), or other specific anemias.
RDW, as part of a comprehensive blood analysis, enables healthcare professionals to assess the size variation of red blood cells, aiding in the diagnosis, monitoring, and treatment of various blood disorders or conditions affecting red blood cells.
