A Comprehensive Guide for MCV Blood Test in Diagnosing Anemia

MCV stands for Mean corpuscular volume and is the measure of the average size of red blood cells. This test is a parameter of Complete blood count.  

Red blood cells can be microcytic, normocytic or macrocytic based on the size.

Need for MCV blood test

1. As part of a Complete blood count to check general health condition.

2. It is a useful test in diagnosing the underlying cause of anemia.

3. To differentiate between iron deficiency anemia and Thalassemia.

Role of mean corpuscular volume test in diagnosing anemia

1. Nutritional deficiency anemia-

Anemia can be due to a deficiency of vitamin B12 and folic acid. Even the B12 absorption issue can cause pernicious anemia. This can be diagnosed by looking at MCV parameters where MCV is high (Macrocytic anemia). However, to confirm the diagnosis peripheral smear and serum B12 assay are required as macrocyic anemia can also be seen in other conditions like liver diseases.

2. Iron deficiency anemia-

This is a major cause of anemia in the pregnancy and adolescence age group. MCV test helps in the diagnosis of iron deficiency anemia as in this MCV has lower value (Microcytic anemia). Peripheral smear and iron studies can confirm the diagnosis of Iron deficiency anemia.

3. Anemia of chronic disease-

In many types of anemia like anemia due to chronic illnesses or kidney diseases the MCV parameter has a lower range or normal range (Microcytic anemia or normocytic anemia). Anemia of chronic disease is also seen in diabetes, malignancies, inflammatory conditions like rheumatological disorder and autoimmune diseases.

4. Anemia due to blood loss-

In case of anemia caused due to significant blood loss the MCV is normal (Normocytic anemia)

5. Normocytic anemia-

The MCV value can be normal in some types of anemia. This is seen in aplastic anemia due to bone marrow failure.

6. Differentiate between Thalassemia and iron deficiency anemia - 

MCV is also a useful parameter in differentiating between iron deficiency anemia and Thalassemia. Mentzer index is derived by dividing MCV with red cell count. If the ratio is less than thirteen, we suspect thalassemia whereas in iron deficiency anemia the ratio is more than thirteen.

To conclude, MCV blood test is a part of red cell indices which with the help of other red cell indices like mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration(MCHC) helps to diagnose different types of anemia and thus helps physicians to treat anemia effectively.