What is Red Blood Cell Distribution Width–Coefficient of Variation (RDW-CV)?
May 14, 2022
Source: Cainiu Health
Dr. Pan Yongyuan
Introduction
Red Cell Distribution Width–Coefficient of Variation (RDW) is a parameter reflecting the variation in red blood cell size and is abbreviated as RDW in routine complete blood count (CBC) reports. In the human body, an abnormal RDW indicates variability in red blood cell volume; interpretation should therefore consider both red blood cell count and hemoglobin levels to determine whether abnormalities are present. In healthy individuals without anemia, the RDW histogram typically displays a well-defined, near-perfect normal distribution.
Among the parameters in a complete blood count (CBC), red blood cells (RBCs), white blood cells (WBCs), platelets, and hemoglobin are particularly important—and their assessment is especially critical. In test results, an elevated coefficient of variation for red blood cell distribution width (RDW-CV) may be observed. This finding warrants careful investigation. But what exactly is the RDW-CV?
What Is the Red Blood Cell Distribution Width Coefficient of Variation (RDW-CV)?
In CBC reports, the red blood cell distribution width coefficient of variation is abbreviated as RDW-CV—a parameter reflecting the variation in red blood cell size (anisocytosis). Within the human body, if RDW-CV is abnormal, it indicates variability in red blood cell volume. Interpretation must therefore integrate other parameters—including RBC count and hemoglobin concentration—to determine whether abnormalities exist.
In healthy individuals without anemia, the RDW histogram displays a well-defined, symmetrical normal distribution. A marked leftward shift in the histogram suggests microcytic hypochromic anemia—most commonly iron-deficiency anemia. Conversely, a rightward shift raises clinical suspicion for megaloblastic anemia (commonly referred to as “megaloblastic anemia”) or myelodysplastic syndromes (MDS). The RDW-CV itself follows a normal distribution; values falling within the normal reference range typically indicate absence of anemia.
Without comprehensive knowledge of the patient’s clinical history and individual circumstances, definitive diagnosis is impossible. We recommend visiting a reputable hospital to undergo further relevant testing, establish a clear diagnosis, and then proceed with appropriate evaluation and management. We hope this explanation has been helpful. Wishing you good health and happiness!
