Mean Corpuscular Volume

MCV stands for mean corpuscular volume — the average size (volume) of your red blood cells. It's a calculated value on the CBC that helps classify anemia and flag nutritional problems. On lab reports you may see it labeled "MCV" or "MCV RBC Auto," where "Auto" just means it was measured automatically by the analyzer, not by hand.

The normal MCV range is about 80–100 fL. Below 80 fL cells are called microcytic (small); above 100 fL they're macrocytic (large). Values inside that window are normocytic.

MCV is reported in femtoliters (fL), an extremely small unit of volume — one femtoliter is a quadrillionth of a liter. So an MCV of 90 means your average red cell has a volume of 90 fL.

Both are within the normal 80–100 fL range. An MCV of 91 is comfortably mid-range. An MCV of exactly 80 sits at the low boundary — normal, but worth pairing with ferritin and iron studies if you're also seeing low hemoglobin, since early iron deficiency shows up as a falling MCV.

MCV sorts anemia by red-cell size. A low MCV (microcytic) points toward iron deficiency or thalassemia; a high MCV (macrocytic) points toward B12 or folate deficiency, alcohol use, or hypothyroidism; a normal MCV (normocytic) suggests chronic disease, blood loss, or a mixed picture. It narrows the search before more targeted tests are ordered.

Not typically. Testosterone drives your marrow to make more red cells, which raises hematocrit and hemoglobin, but it doesn't change their average size much. A persistently abnormal MCV usually reflects a separate nutritional or hematologic issue worth investigating on its own — for example, iron depletion from frequent blood donation can nudge MCV down over time.