This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Medicine
[{'content': 'Best marker of iron deficiency anemia is? \nSelect and explain. \nA. Serum iron, B. Serum ferritin, C. Total iron binding capacity, D. Transferrin saturation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: ANSWER: (B) Serum ferritinREF: Harrison\'s 18th ed ch: 103"Serum ferritin is the most specific and sensitive test for iron deficiency"Under steady-state conditions, the serum ferritin level correlates with total body iron stores; thus, the serum ferritinlevel is the most convenient laboratory test to estimate iron stores.', 'role': 'assistant'}]