The note about dimorphic RBC is made when there are two distinct groups of RBC's This can occur following iron supplementation when a surge in production of RBC's produces a group of immature RBC's following a reduction in RBC production. There are some other explanations for a dimorphic distribution (like blood transfusion) but in this clinical picture the doctors probably ruled those out. They would also have considered the ratios like RDW to help interpret this lab result since those would help indicate the extent to which the distribution was normal or skewed.
http://www.perthhaematology.com.au/IronStudies.pdf
This is a very helpful the interpretation of iron studies. You sound very well educated on the subject already but you may find some of this information new or different than what you have seen before. For example, low ferritin, low transferrin sat % and low serum iron are all signs of iron deficient anemia. Low or dropping ferritin is considered a very strong indicator of iron deficient anemia. This is not to say she does not also have anemia of chronic disease. But if her ferritin is dropping then iron deficiency looks like it may be the most likely cause. Consulting her doctor, as you have done, is always the best course when there are unusual lab results like these.
I would also point out that under most circumstances there are additional signs that her disease is not in good remission. My son's labs are often perfect or near perfect even though he is flaring so I completely understand that labs may not be a helpful tool for some children.
But this is not the case for most kids with Crohn's.
Other lab values to consider as markers of inflammation, preferably viewed as a pattern from lab values taken in series over a period of several weeks to months/years, would include falling/low albumin, rising/elevated platelets (doctors sometimes call this the "poor man's ESR" as it is a rough measure of inflammation), high/rising ESR and CrP of course, high/rising WBC.
The WBC diff may show rising abs. monocytes and abs. lymphocytes although lymphocyte counts can be suppressed by steroids.
When doing iron supplementation, it is good to avoid giving it with dairy products within 1 hour before and 2 hours afterwards and to give it with food to reduce gut irritation. We have found it to work best in a combination of Vit. C and Vit B (called a Stress relief formula here). Iron appears to be best absorbed when these vitamins are present in the gut as well but the research on this is unclear. But our experience does support this approach.
Hope her symptoms continue to improve.
