Rosh Internal Medicine Boost Practice Exam

Macrocytic anemia is characterized by the presence of enlarged red blood cells (macrocytes) in the bloodstream, which often results from impaired DNA synthesis during red blood cell production. One of the most common causes of macrocytic anemia is Vitamin B12 deficiency.

Vitamin B12 plays a crucial role in the synthesis of DNA, particularly in the formation of red blood cells in the bone marrow. When there is insufficient Vitamin B12, red blood cells do not mature properly, leading to the production of larger-than-normal cells. This can ultimately result in anemia since the proper number of healthy red blood cells is not produced.

Folate deficiency is another cause of macrocytic anemia, as folate is also essential for DNA synthesis. However, the question asks for a common cause, and Vitamin B12 deficiency is widely recognized as a prevalent and significant cause of macrocytic anemia, especially in certain populations, such as the elderly or those with gastrointestinal absorption issues.

Iron deficiency anemia, in contrast, typically leads to microcytic anemia, characterized by smaller-than-normal red blood cells. Chronic disease can also contribute to anemia but is more commonly associated with normocytic anemia rather than macrocytic. Therefore, Vitamin B12 deficiency is the most directly