Table 152.2MCV and RDW in the Evaluation of Anemias

Red cell size as defined by MCV
RDWDecreased (microcytic; low MCV)Normal (normocytic; MCV = N)Increased (macrocytic; high MCV)
Normal (little or no anisocytosis)Heterozygous thalassemiasPoor iron utilizationLiver disease
Acute blood lossAplastic anemia
Anemia of chronic disease (hypoproliferative)Enzyme defects (e.g., G6PD deficiency)Myelodysplastic syndrome
Acute hemolysis
Liver disease
Increased (anisocytosis)Iron deficiencyEarly iron deficiencyMegaloblastic
Red cell fragmentationEarly megaloblasticSideroblastic
SideroblasticMyelodysplastic syndrome
MyelophthisisSecondary to chemotherapy
Combined deficiency
Sickle cell anemia
Immune hemolysisa
Secondary to chemotheraphy

MCV may be falsely elevated due to cell agglutination, usually with cold agglutinins.

From: Chapter 152, Red Cell Indices

Cover of Clinical Methods
Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.
Walker HK, Hall WD, Hurst JW, editors.
Boston: Butterworths; 1990.
Copyright © 1990, Butterworth Publishers, a division of Reed Publishing.

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