If a patient has microcytic anemia with normal RDW and normal RBC count, what is the likely diagnosis?

In the context of microcytic anemia characterized by a normal red cell distribution width (RDW) and normal red blood cell (RBC) count, the most likely diagnosis is thalassemia. The key features in this scenario are the microcytic nature of the anemia coupled with the normal RDW.

Thalassemia, particularly beta-thalassemia trait, is commonly associated with microcytic anemia. In thalassemia, the production of hemoglobin is affected due to genetic defects, leading to smaller red blood cells. However, because thalassemia is a microcytic process that affects the synthesis of hemoglobin without causing variable sizes of red blood cells, the RDW remains normal. This contrasts with several other types of anemia where you would typically see an increase in RDW due to variations in cell size.

In cases of iron deficiency anemia, for example, there is usually a low RDW as the body dynamically adjusts to iron levels; the RDW often increases as the anemia progresses. Chronic disease anemia and lead poisoning also typically present with increased RDW. Thus, the combination of microcytic anemia with normal RDW and normal RBC count supports the diagnosis of thalassemia rather than other types of