American Board of Internal Medicine (ABIM) Certification Practice Exam

What are common characteristics of β-thalassemia?

1. Hemolytic anemia and microcytosis

2. Macrocytic anemia and leukocytosis

3. Iron overload and thrombocytopenia

4. Reticulocytosis and hypersegmented neutrophils

The correct answer is: Hemolytic anemia and microcytosis

β-thalassemia is a genetic blood disorder characterized by reduced production of hemoglobin due to mutations in the β-globin gene. This reduction leads to ineffective erythropoiesis and hemolytic anemia, which is one of the hallmark features of the disease. Patients with β-thalassemia commonly present with hemolytic anemia due to the destruction of abnormal red blood cells that are produced in insufficient quantities. The red blood cells that are produced tend to be smaller than normal, leading to microcytosis, which is a key laboratory finding. The other options describe conditions or properties that are not typically associated with β-thalassemia. For instance, macrocytic anemia is more indicative of conditions such as vitamin B12 or folate deficiencies, while leukocytosis involves an increase in white blood cells, which is not characteristic of β-thalassemia. Iron overload, often due to repeated blood transfusions, and thrombocytopenia, which refers to a low platelet count, can occur in more advanced stages or as complications of treatment but are not defining features of the disorder itself. Reticulocytosis, the presence of young red blood cells in the bloodstream, can occur in response to anemia but is not specific to β