For those who are taking the iron supplement and do not have an obvious explanation for lack of an increase in hemoglobin level and iron stores, it may be prudent to screen for celiac disease and/or Helicobacter pyloriinfection, both of which have been implicated in reduced oral iron absorption. Celiac disease in particular has additional management implications if present
Some individuals whose anemia does not respond to oral iron due to an inflammatory block may benefit from IV iron. This has been demonstrated in various trials in various populations. As examples:
●A series of 812 patients with iron deficiency who were unable to tolerate oral iron or whose hemoglobin did not increase with oral iron were randomly assigned to receive IV iron (ferumoxytol, two 510 mg doses one week apart) versus placebo [83]. Compared with placebo, patients who received IV iron were more likely to have an increase in hemoglobin of ≥2 g/dL at week 5 (6 versus 81 percent). Other endpoints such as hemoglobin ≥12 g/dL and functional fatigue score also favored the IV iron arm
Other individuals may have additional diagnoses, either initially misdiagnosed as iron deficiency, concomitant with iron deficiency, or rarely, developing during treatment of iron deficiency. Examples include nutrient deficiencies (vitamin B12, folate), bone marrow abnormalities (myelodysplastic syndrome), inherited anemias (thalassemia, enzyme defects), hypothyroidism, other genetic conditions that affect iron balance such as iron-resistant iron deficiency anemia (IRIDA), and disorders associated with chronic inflammation.