Which laboratory pattern is most consistent with thalassemia rather than iron deficiency?

• A. Macrocytic anemia with normal serum iron
• B. Microcytic anemia with normal/elevated serum iron or no response to iron treatment
• C. Macrocytic anemia with high MCV
• D. Normocytic anemia with normal iron

Answer: (B)

Thalassemia presents as a microcytic, hypochromic anemia due to deficient globin synthesis, but unlike iron deficiency, iron stores are not depleted. Lab clues are microcytosis with normal or even elevated serum iron (and normal ferritin), and the anemia does not improve with iron therapy. This lack of response to iron helps distinguish thalassemia from iron deficiency, where iron studies are low and therapy typically corrects the anemia. Therefore, a microcytic anemia with normal or high serum iron or no response to iron treatment best fits thalassemia.