An 18-year-old man is seen in the clinic for routine assessment. He reports no active symptoms, there is no past medical history and he is not taking any medications. He mentions that his brother has a "low blood count" that is hereditary but does not recall the name of the disorder.His physical examination is entirely normal. A complete blood count reveals a hemoglobin of 10.5 g/dL and microcytic red cells on the blood film. A hemoglobin electrophoresis confirms the diagnosis of beta-thalassemia minor. Which of the following findings is characteristic of this condition?
High-Yield Explanation
An increased amount of HbF or HbA2 is present in patients with beta-thalassemia. As the hemoglobin beta-chains are decreased in beta-thalassemia, the excess alpha-chains combine with gamma-and delta-chains to make HbF and HbA2, respectively. Increased osmotic fragility of red cells is a feature hereditary spherocytosis and not thalassemia. Most patients with thalassemia have normal quantities of bone marrow iron, and HbS is not a feature of thalassemia but of sickle cell disease.