This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'Which of the following haemoglobin (Hb) estimation will be diagnostically helpful in the case of beta thalassemia trait – \nSelect and explain. \nA. Hb–F, B. Hb1–C, C. Hb–A2, D. Hb–H', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hemoglobin A2\n\nIn hemoglobin A2 the polypeptide consists of two a and two δ chains i.e. the β chain of the normal adult hemoglobin is replaced by the\xa0δ\xa0chain.\nIn normal adults, hemoglobin A2 is present in trace amounts. It accounts for 1.5% to 3.5% of the normal adult hemoglobin.\n\nThe clinical implication of HbA2 \nHbA2 levels have special application in the diagnosis of β thalassemia trait. \n\nElevation of HbA2 is present in these cases even through the peripheral blood smear is normal.\nMicrocytosis and other morphological characteristics of β-thalassemia trait are also seen it iron deficiency but unlike β thalassemia trait HbA2 level is decreased.', 'role': 'assistant'}]