Which term refers to larger than normal red blood cells, typically seen in liver disease, hypothyroidism, megaloblastic anemia, chemotherapy, post-splenectomy, and high reticulocyte count?

• A. Leukopoiesis
• B. Macrocytes
• C. Macrophages
• D. Megaloblasts

Answer: (B)

Macrocytosis is the idea here: red blood cells that are larger than normal. Macrocytes are the circulating RBCs that show this size increase, and the term describes that change in cell size.

These conditions commonly feature macrocytosis because they affect how RBCs mature or how many immature, larger cells are present. In liver disease and hypothyroidism, metabolic or membrane changes can produce bigger erythrocytes. Megaloblastic anemia involves defective DNA synthesis in developing RBCs, leading to enlarged precursors and, as a result, larger circulating cells. Some chemotherapy regimens disrupt DNA synthesis in rapidly dividing cells, producing macrocytosis as well. After splenectomy, the spleen’s filtering role is reduced, allowing more larger RBCs and reticulocytes to remain in circulation. A high reticulocyte count directly contributes to larger average RBC size because reticulocytes are inherently bigger than mature red cells.

Megaloblasts are large bone marrow precursors, not the mature circulating cells themselves, so the term for larger circulating RBCs is macrocytes.