Mean corpuscular volume
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The mean corpuscular volume, or MCV, is a measure of the average red blood cell volume that is reported as part of a standard complete blood count.
In patients with anemia, it is the MCV measurement that allows classification as either a microcytic anemia (MCV below normal range) or macrocytic anemia (MCV above normal range).
It can be calculated by multiplying the hematocrit percentage by ten, and dividing the product by the RBC (red blood cell) count. The result is typically reported in femtoliters.
If the MCV was determined by automated equipment, the result can be compared to RBC morphology on a peripheral blood smear. Any deviation would be indicitive of either faulty equipment or technician error.
The normal range is typically 80-96 fl. In pernicious anemia (macrocytic), MCV can range up to 150 femtoliters. An enlarged MCV is also associated with alcoholism1 (as are an elevated GGT and a ratio of AST:ALT of 2:1). In iron deficiency anemia (microcytic), it can be as low as 60 to 70 femtoliters.
References
1. Tonnesen H, Hejberg L, Frobenius S, Andersen JR. Erythrocyte mean cell volume--correlation to drinking pattern in heavy alcoholics. Acta Med Scand. 1986;219(5):515-8. PMID 3739755