What is megaloblastic anemia?

What is megaloblastic anemia?

• A. A type of anemia where RBCs are abnormal and large
• B. A type of anemia where RBCs are small
• C. A type of anemia caused by iron overload
• D. A type of anemia with normal RBC size

Answer: (A)

Megaloblastic anemia is a macrocytic form of anemia caused by impaired DNA synthesis in developing red blood cells, so the marrow makes oversized, abnormal cells called megaloblasts and the circulating RBCs are larger than normal. The common cause is deficiency of vitamin B12 or folate, which disrupts DNA replication and leads to asynchrony between the nucleus and cytoplasm during maturation. That’s why the defining feature is RBCs that are abnormal and large. By comparison, microcytic anemia has small RBCs (as seen with iron deficiency), iron overload isn’t a cause of megaloblastic changes, and normal-sized RBCs describe normocytic anemia.

Megaloblastic anemia is a macrocytic form of anemia caused by impaired DNA synthesis in developing red blood cells, so the marrow makes oversized, abnormal cells called megaloblasts and the circulating RBCs are larger than normal. The common cause is deficiency of vitamin B12 or folate, which disrupts DNA replication and leads to asynchrony between the nucleus and cytoplasm during maturation. That’s why the defining feature is RBCs that are abnormal and large. By comparison, microcytic anemia has small RBCs (as seen with iron deficiency), iron overload isn’t a cause of megaloblastic changes, and normal-sized RBCs describe normocytic anemia.