Which erythrocyte abnormality is characterized by an increased number of target cells?

Target cells, also known as codocytes, are characterized by a central area of hemoglobin surrounded by a ring of clear cytoplasm, giving them a target-like appearance when viewed under a microscope. The presence of an increased number of target cells is primarily associated with specific forms of anemia, particularly thalassemia.

In thalassemia, the synthesis of hemoglobin is impaired, leading to an imbalance in the production of its globin chains. As a result, the erythrocytes often develop structural abnormalities, including increased surface area relative to their volume. This abnormality can manifest as target cells due to the reduced hemoglobin content in the cells, which creates a central zone of pallor surrounded by the hemoglobin-rich cytoplasm.

In contrast, while other anemias may feature various types of red cell abnormalities, such as microcytosis in iron deficiency anemia or macrocytosis in pernicious anemia, they do not typically present with an increased number of target cells. Aplastic anemia is characterized by a reduction in the number of all types of blood cells (pancytopenia) and does not specifically lead to the formation of target cells. Therefore, thalassemia is the correct answer, as it is the