The MCV blood test is part of a complete blood count (CBC). MCV stands for “mean cell volume" or mean corpuscular volume. It is a measure of the average size of red blood cells (RBC), also called erythrocytes. Knowing your MCV is important to assure that you are in good health. It is also a good way to discover if you have an illness that may still be asymptomatic. Asymptomatic means that you do not yet feel any symptoms.
A CBC is performed by extracting blood in a vein, usually in your upper extremity, in the elbow area. Blood is drawn via a syringe. It could also be drawn by fingerprick or heelprick. Fingerprick is usually used for infants and young children, while heelprick is for newborn babies. Once the blood is drawn, it is sent in the laboratory for analysis.
MCV is measured in fL or femtoliters. The normal value is about 80 to 100 fL, although the normal range may vary slightly from different laboratories. Your MCV will be increased if your RBCs are macrocytic. This means that they are larger than their normal size. If your RBCs are microcytic, the MCV is below normal value. Microcytic means that your RBCs are smaller than their usual size.
RBCs play a critical role in the body. The primary function of RBCs is to transport hemoglobin. Hemoglobin carries oxygen from the lungs towards tissues around the body. These RBCs also help excrete carbon dioxide from the body. These cells bring carbon dioxide from the tissue to the lungs, where it can be expelled.
MCV is elevated in conditions such as hemolytic anemia, pernicious anemia and anemia caused by deficiencies in vitamin B12 and folic acid. MCV could also be elevated in people who are heavy alcoholic drinkers. MCV is below its normal range in people suffering from thalassemia, chronic diseases or iron deficiency anemia. For patients with bloody stool, a low MCV value could indicate a possible cancer in the gastrointestinal system.