A raised MCV, or mean corpuscular volume, means the red blood cells are larger than they should be, explains the American Association for Clinical Chemistry. Counting red blood cells and measuring their size helps diagnose different types of anemia.
A normal MCV value ranges from 80 to 100 femtoliter, states MedlinePlus. A person with an MCV greater than normal is said to have macrocytosis. The causes of macrocytosis include folate deficiency, vitamin B-12 deficiency, alcoholism, hypothyroidism and liver disease, notes Mayo Clinic. Losing a large amount of blood prompts the bone marrow to produce extra red blood cells, causing macrocytosis in some people. Medications used to treat autoimmune disorders and cancer also have the potential to increase MCV.
MCV is determined during a complete blood count, reports the American Association for Clinical Chemistry. The complete blood count provides information about platelets, red blood cells and white blood cells. Because MCV and MCH, mean corpuscular hemoglobin, are closely related, they are often used together to diagnose certain medical conditions. MCH measures the average amount of hemoglobin in a red blood cell. Hemoglobin is the protein that carries oxygen through the blood. Larger red blood cells tend to have more hemoglobin in them, so a person with an increased MCV is likely to have an increased MCH.