This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Anatomy
[{'content': 'Most sensitive and specific test for diagnosis of iron deficiency is \nSelect and explain. \nA. Serum iron levels, B. Serum ferritin levels, C. Serum transferrin receptor population, D. Transferrin saturation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref Harrison 19 th ed pg 627,628 Under steady-state conditions, the serum ferritin level correlates with total body iron stores; thus, the serum ferritin level is the most convenient laboratory test to estimate iron stores. The normal value for ferritin varies according to the age and gender of the individual', 'role': 'assistant'}]