What is the main characteristic of macrocytic anemia?

The main characteristic of macrocytic anemia is an increased mean corpuscular volume (MCV). This condition is defined by the presence of abnormally large red blood cells. In macrocytic anemia, the MCV is typically greater than 100 fL, indicating that the red blood cells are larger than normal.

This increase in cell size often results from impaired DNA synthesis, which can be caused by deficiencies in vitamin B12 or folate. These vitamins are essential for proper cell division, and their lack leads to the production of oversized erythrocytes that cannot function effectively.

In contrast, decreased or normal MCV values are associated with other types of anemia, such as microcytic anemia (where MCV is decreased) or normocytic anemia (where MCV remains within the normal range). An increased reticulocyte count can be seen in various conditions, such as hemolytic anemia or recent blood loss, but it is not a characteristic exclusive to macrocytic anemia. Therefore, the hallmark of macrocytic anemia is indeed an increased MCV.