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
The most suitable test to assess iron stores is - 
Select and explain. 
A. Serum iron, B. Serum ferritin, C. TIBC, D. Transferrin saturation
B: Serum ferritin
Answer: B: Serum ferritin 
Explanation: Ans. is 'b' i.e., Serum ferritin o Best test for the assessment of Iron stores is serum ferritin.o Serum ferritin is the earliest indices to decrease in Iron deficiency anemia.o It is the most sensitive test for the diagnosis of iron deficiency anemia.o Earliest marker for the diagnosis of Iron deficiency anemia.o Serum ferritin is the earliest marker for the detection of Iron deficiency anemiaSerum ferritin - Serum iron - Transferrin - Total iron binding capacity - % saturation