MCV — Normal Range & Interpretation

Clinical Context

Mean corpuscular volume (MCV) measures the average size of red blood cells in femtoliters. Clinicians use MCV to classify anemia into microcytic, normocytic, and macrocytic categories, which narrows the differential diagnosis and directs the workup before ordering more expensive studies like iron panels, B12, or folate levels.

A low MCV under 80 fL points to microcytic anemia, most often from iron deficiency in menstruating women, children, and patients with chronic GI blood loss. Thalassemia and anemia of chronic disease also produce microcytosis. An elevated MCV above 100 fL signals macrocytic anemia, classically from vitamin B12 or folate deficiency, alcohol use disorder, hypothyroidism, liver disease, or medications such as methotrexate, hydroxyurea, and zidovudine. Reticulocytosis after acute blood loss or hemolysis also elevates MCV.

On the AANP exam, expect to match MCV patterns to likely etiologies in vignette questions. Recognize that iron deficiency lowers MCV while B12 and folate deficiencies raise it, and order ferritin for microcytosis and B12 with folate for macrocytosis. Expect questions linking macrocytic anemia with neurologic symptoms to B12 deficiency rather than folate, since this distinction guides treatment and prevents permanent neurologic damage from isolated folate repletion.

Practice Questions

Related Labs

• WBC — /μL
• RBC — /μL
• Hemoglobin (Hgb) — g/dL
• Hematocrit (Hct) — %
• Platelets — /μL

Sources

• MedlinePlus
• ARUP Consult