What is the characteristic finding in the peripheral smear of a patient with iron deficiency anemia?

In cases of iron deficiency anemia, the characteristic finding in a peripheral blood smear is microcytosis and hypochromia. Microcytosis refers to the presence of smaller-than-normal red blood cells, while hypochromia indicates that these cells have reduced hemoglobin content, which typically presents as a paler appearance when viewed under a microscope.

Iron deficiency anemia occurs when there is insufficient iron available for hemoglobin synthesis, leading to a decreased production of hemoglobin. As a result, the red blood cells that are produced are smaller and contain less hemoglobin than normal, hence the microcytic and hypochromic features. This morphology reflects the body's attempt to adapt to limited iron availability and is a direct consequence of the reduced synthesis of hemoglobin.

In contrast, other options like target cells (often associated with conditions such as liver disease or thalassemia), normocytes (which are normal-sized red blood cells typically seen in conditions where the erythropoiesis is adequate), or macrocytosis (which indicates larger red blood cells and is typically seen in vitamin B12 or folate deficiency) do not represent the typical findings associated with iron deficiency anemia. Thus, the presence of microcytosis and hypochrom