A 52-year-old man is complaining of fatigue. His physical examination is normal, but his hemoglobin is low at 8.9 mg/dL. The reticulocyte count is 0.5 %, serum iron and TIBC are normal, and ferritin is elevated. A bone marrow aspirate reveals erythroid precursors that have accumulated abnormal amounts of mitochondrial iron.For the above patient with a hypochromic microcytic anemia, select the most likely diagnosis.

Erythroid precursors that have accumulated abnormal amounts of iron are called ringed sideroblasts. Sideroblastic anemia can be either inherited or acquired. Common acquired causes are ingestion of certain drugs, alcohol, or toxins such as lead or zinc. The beta-thalassemia trait is diagnosed by demonstrating an elevated HbA2, iron deficiency by iron studies and ferritin levels, and anemia of chronic disease by demonstrating a chronic disease. Sideroblastic anemia generally requires a bone marrow aspiration revealing ringed sideroblasts for diagnosis.