 In early iron deficiency, there are very subtle changes that one ought to look for in the automated blood count, which might not catch the eye on the blood smear, except you have already biased your mind with the results of the automated blood count. Keep in mind that there is a delay in cytoplasmic maturation, and this delay in cytoplasmic maturation is unprogrammed, so it doesn't follow a pattern. And so the first thing you would notice would be the variation in sizes of the red blood cell, and this shows in an increased red cell distribution width. So bear in mind again that the earliest change may very well and may only be that increased variation of cell size, that is the RDW.