This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Megaloblastic Anemia, Subject name: Pathology
[{'content': 'A 60-year-old man presents with a 6-month history of increasing fatigue. Physical examination reveals marked pallor, and a CBC shows a macrocytic anemia. Which of the following is the most likely cause of anemia in this patient? \nSelect and explain. \nA. Alcoholism, B. Chronic disease, C. Iron deficiency, D. Renal disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: - Macrocytic anemia can be caused by folate & Vit B12 deficiency. - Conditions associated with their deficiency are: Malnutrition - Alcoholics, vegans etc Decreased intrinsic factor, pancreatic & ileal diseases. Fish tape worm infection. Blind loop syndrome Increased requirement like children, pregnancy, lactation etc Drugs like methotrexate, OCP etc -Interfere with Folate metabolism - As the question states an elderly man with malnutrition, most appropriate cause of macrocytic anemia is chronic alcoholism. - Remaining options - Chronic diseases, iron deficiency & renal diseases may present with microcytic anemia not macrocytic.', 'role': 'assistant'}]