Red Blood Cell Indices
- Mean Corpuscular Volume (MCV) is the average red cell volume, calculated with the following formula:
-> MCV = (HCT/RBC) x 10
Most anemias are categorized by MCV as normocytic, microcytic, or macrocytic. - Red Cell Distribution Width (RDW) measures the variation in cell size. Increased RDW indicates anisocytosis.
- Mean Corpuscular Hemoglobin (MCH) is the average hemoglobin content in a red cell, calculated with the following formula:
-> MCH = (Hgb/RBC) x 10 - Mean Corpuscular Hemoglobin Concentration (MCHC) is the average concentration of hemoglobin in a red cell, calculated with the following formula:
-> MCHC = (Hgb/Hct) x 100
MCHC takes red cell size into consideration, making it much more useful than MCH in classifying anemia as hypochromic, as many anemias also affect MCV.
Normocytic / Normochromic
Normocytic: MCV 80-100 fL
Cells should be about the size of the nucleus of a small resting lymph (80-100 fL)
Normochromic: MCHC 32-36 g/dL
Central pallor should be less than 1/3 of the RBC
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Anisocytosis
RDW increased (variation in cell size)
May have dimorphic cell population.
Microcytosis
MCV < 80 fL (decreased)
Seen in Iron Deficiency Anemia, Anemia of Chronic Inflammation, Sideroblastic Anemia, Thalassemia
Macrocytosis
MCV > 100 fL
If cell is polychromatophilic, it may be a retic (See polychromasia for more info.)
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Hypochromasia
MCHC <32 g/dL (decreased)
Increased central pallor.
Usually (but not always) microcytic.
Seen in Iron Deficiency Anemia, Sideroblastic Anemia, Anemia of Chronic Inflammation, Thalassemia
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