The high RDW and the lower than usual for thal minor MCV and MCH, both suggest iron may also be low. If your iron studies show you are low, iron should be given again. For the long term, because there may be an absorption issue after the bypass, you could try iron water, a supplement that is water with a natural high iron content. It is more easily absorbed than most supplements and would be worth a try to see if you can keep your iron stores up without IV's. It is sold under the name, Spatone. In spite of your thal minor, if there is an ongoing iron absorption proble, you may need to regularly take a supplement.