An elevated RDW on a CBC indicates which finding about red blood cells?

An elevated RDW on a CBC indicates which finding about red blood cells?

• A. Increased variation in size (anisocytosis)
• B. Increased mean corpuscular hemoglobin
• C. Decreased red cell distribution
• D. Increased platelet indices

Answer: (A)

RDW measures how much red blood cell sizes vary from one another. When RDW is elevated, it means there is increased variation in size among RBCs, a condition called anisocytosis. This happens when the blood contains a mix of small and large cells—for example, iron deficiency can produce microcytes while reticulocytes or certain nutrient deficiencies produce macrocytes, resulting in a wider spread of cell sizes. The mean corpuscular hemoglobin reflects the average hemoglobin per cell, not how varied the cell sizes are, so it wouldn’t explain an elevated RDW. Platelet indices pertain to platelets, not red cells. So the elevated RDW specifically points to anisocytosis.

RDW measures how much red blood cell sizes vary from one another. When RDW is elevated, it means there is increased variation in size among RBCs, a condition called anisocytosis. This happens when the blood contains a mix of small and large cells—for example, iron deficiency can produce microcytes while reticulocytes or certain nutrient deficiencies produce macrocytes, resulting in a wider spread of cell sizes. The mean corpuscular hemoglobin reflects the average hemoglobin per cell, not how varied the cell sizes are, so it wouldn’t explain an elevated RDW. Platelet indices pertain to platelets, not red cells. So the elevated RDW specifically points to anisocytosis.