A 25-year-old woman of Mediterranean descent has Hb 7.2 g/dL, MCV 62 fL, target cells on peripheral smear, and HbA2 of 5.8% on HPLC. Serum iron and ferritin are normal. What is the diagnosis?

• A Iron deficiency anemia
• B Hemoglobin E disease
• C Alpha-thalassemia trait
• D Beta-thalassemia trait ✓

Explanation

Beta-thalassemia trait is characterized by mild microcytic hypochromic anemia, elevated HbA2 (>3.5%, typically 4–7%) on HPLC, target cells, and normal iron studies. HbA2 elevation is the diagnostic hallmark. Iron deficiency also causes microcytosis but shows low ferritin/serum iron and normal or low HbA2. Alpha-thalassemia trait shows normal HbA2 and Hb H inclusions may be seen. Hemoglobin E disease shows elevated HbE peak on HPLC, not HbA2.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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