About Mean Corpuscular Volume
MCV (Mean Corpuscular Volume) measures the average size of red blood cells and is the key index for classifying the type of anaemia. Low MCV (microcytic anaemia) is caused by iron deficiency or thalassaemia; high MCV (macrocytic anaemia) is caused by vitamin B12 or folate deficiency; normal MCV with anaemia (normocytic) points to chronic disease, haemolysis, or bone marrow failure. MCV is one of the first CBC values to change in developing deficiencies, often preceding the haemoglobin drop by months.