Most sensitive and specific test for diagnosis of iron deficiency is:
Serum iron level
Serum ferritin levels
Serum transferrin receptor populations
Transferrin saturation
b. Serum ferritin levels(Ref: Nelson's 20/e p 2323-2325, Ghai 8/e p 334-335)Low serum ferritin level invariably indicates iron deficiency and hence it is the most specific and sensitive test for iron deficiency anemia.
C.V.S.