LAUSR

Awidely used anemia classification system subdivides anemia as microcytic, normocytic, or macrocytic, according to the mean corpuscular volume (MCV) of the red blood cell. The most common etiology for megaloblastic anemia, a subset of macrocytic anemia, is vitamin B12 and folate deficiencies, and it is characterized by marked macrocytosis (i.e., MCV above 110fL). Interestingly, the literature regarding the role of B12 and folate deficiencies in marked macrocytosis is limited. In the past decades, over-the-counter supplementation for folate and vitamin B12 has become common. The USA began mandatory folic acid fortification in 1998, reducing folate deficiency prevalence. Considering these trends, we evaluated the extent to which serum folate and vitamin B12 determine marked macrocytic anemia.