In anemia, the body has a reduced quantity of red blood cells. One of the best ways to classify anemia is by the MCV, or mean corpuscular volume, which is expressed in femtoliters (fL). The MCV helps you think about the cause of the anemia and how to evaluate for it:
Microcytic anemias (low MVC, Think TAIL: thalassemia, anemia of chronic disease, iron deficiency anemia, lead poisoning.
Macrocytic anemias (high MCV, > 100 fL): Think BILL: B12 deficiency, impaired liver function, low folate levels, low thyroid levels.
Normocytic anemias (normal MCV, 80–99 fL): Think RAM: renal dysfunction, anemia of chronic disease (also can cause a low MCV), malignancy or myelopthisic anemia.
