 [ Symptoms ] what is mcv [ Disease ] mcv stands for mean corpuscular volume it is the average volume of the body is red blood cells measured in femtoliters one quadrillionth of a liter cell counting machines calculate mcv from a blood sample a normal value may vary between laboratories but is usually between 80 and 96 femtoliters fl an mcv above 100 fl is called macrocytosis when anemia low red blood cell count is also present it is called a macrocytic anemia causes of macrocytic anemia include deficiency of b12 or folic acid medication side effects alcohol abuse and certain blood cancers macrocytic anemia can also occur in healthy people who are rebuilding their blood supply after surgery for example an mcv below 80 fl is called microcytosis or microcytic anemia if the red blood cell count is also low microcytic anemia can be due to iron deficiency blood loss in women most often from menstruation chronic illness or a condition causing abnormal hemoglobin like sickle cell disease or thalassemia it is not unusual to have an mcv that is slightly abnormal without any serious condition identified as a cause often in these cases the mcv becomes normal again on its own when it is next tested