<prompt> 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?AlcoholismChronic diseaseIron deficiencyRenal disease  <response>: - 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. 