In the morphologic classification of anemias, which parameter is used to distinguish between microcytic and normocytic anemias?
A. Hemoglobin concentration (Hb)
B. Mean corpuscular volume (MCV)
C. Mean corpuscular hemoglobin (MCH)
D. Red cell distribution width (RDW)
Explanation
Morphologic Classification of Anemias
Key Point
The morphologic classification of anemias is based on mean corpuscular volume (MCV), which reflects the average size of red blood cells. This is the primary parameter used in the initial laboratory workup of any anemia.
MCV-Based Classification
Table
Classification
MCV Range
Common Causes
Microcytic
<80 fL
Iron deficiency, thalassemia, sideroblastic anemia, anemia of chronic disease (early)
MCV is the single most useful parameter for initial classification and differential diagnosis of anemia. It guides the next step in investigation (iron studies, B12/folate levels, reticulocyte count, hemolysis workup).
Mnemonic: MICROCYTIC ANEMIAS — "TAILS"
Thalassemia
Anemia of chronic disease
Iron deficiency
Lead poisoning (sideroblastic)
Sideroblastic anemia
Why Other Parameters Are Secondary
MCH (Mean Corpuscular Hemoglobin): Reflects hemoglobin content per RBC; correlates with MCV but is not the primary classifier
RDW (Red Cell Distribution Width): Measures variation in RBC size; useful for detecting mixed anemias but not the primary morphologic classifier
Hemoglobin concentration: Defines anemia severity, not cell size
Practice similar questions
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.
