The serum ferritin is a more sensitive test than the serum iron or TIBC for iron deficiency and for iron overload.2 When all these tests are used together, as is often necessary, they usually can distinguish between iron deficiency anemia and the anemia of chronic disease. The best and most reliable evaluation of total body iron stores is by bone marrow aspiration and biopsy.
Without having a bone marrow aspiration, the best way to determine if you are iron deficient may be whether or not your anemia and general energy level respond to iron supplementation.