A 25-year-old woman has a 3-year history of arthralgias. Physical examination shows no joint deformity, but she appears pale. Laboratory studies show a total RBC count of 4.7 million/ mm3, hemoglobin of 12.5 g/dL, hematocrit of 37.1%, platelet count of 217,000/ mm3, and WBC count of 5890/ mm3. The peripheral blood smear shows hypochromic and microcytic RBCs. Total serum iron and ferritin levels are normal. Hemoglobin electrophoresis shows 93% hemoglobin A1 with elevated hemoglobin A2 level of 5.8% and hemoglobin F level of 1.2%. What is the most likely diagnosis?

Although b-thalassemia minor and iron deficiency anemia are both characterized by hypochromic and microcytic RBCs, there is no increase in hemoglobin A2 in iron deficiency states. A normal serum ferritin level also excludes iron deficiency. In contrast to b-thalassemia major, there is usually mild anemia without major organ dysfunction with b-thalassemia minor. Diseases that produce hemolysis and increase erythropoiesis (e.g., autoimmune hemolytic anemia, malaria) do not alter the composition of b-globin chain production. Anemia of chronic disease may mimic iron deficiency and thalassemia minor with respect to hypochromia and microcytosis; however, anemia of chronic disease is associated with an increase in the serum concentration of ferritin.