Inadequate response to oral iron therapy

An inadequate response to oral iron therapy may be due to a number of reasons as outlined in the table below with more than one factor often being involved.

  • Patient not taking oral iron therapy

  • Patient taking an iron supplement or multivitamin tablet with insufficient iron content

  • Concomitant consumption of inhibitors of iron absorption (eg, tea, calcium, antacids, tetracycline, within 2 hours of iron ingestion)

  • Coexisting inflammation with functional iron deficiency

  • Intestinal mucosal disorders (eg, coeliac disease, inflammatory bowel disease)

  • Impaired gastric acid secretion (including use of proton pump inhibitors)

  • Gastric/intestinal bypass procedures

  • Helicobacter pylori colonisation

  • Controlled-release iron formulations may contribute (ie, potential for limited iron absorption in some patients)

  • Occult, undiagnosed or recurrent gastrointestinal blood loss (eg, peptic ulcer, malignancy, angiodysplasia, small bowel lesion, parasites)

  • Other source of recurrent blood loss (eg, menorrhagia due to uterine pathology or an inherited bleeding disorder such as von Willebrand disorder)

  • Multiple sources of recurrent blood loss (eg, hereditary haemorrhagic telangiectasia)

  • Ongoing urinary iron losses (eg, significant valve haemolysis)

  • Renal failure responding to erythropoietin-stimulating agents

  • Superimposed infection, inflammation, malignancy or renal failure

  • Concomitant B12 or folate deficiency

  • Coexisting primary bone marrow disease or suppression

  • Anaemia of chronic disease or renal failure
  • Haemoglobinopathy
  • Other causes of anaemia (eg, haemolysis, myelodysplastic syndromes, congenital anaemia, endocrine disorders)

Iron-refractory iron-deficiency anaemia (IRIDA) is a recently discovered, rare, autosomal recessive disorder that is unresponsive to treatment with oral iron. It represents less than 1% of the cases of iron-deficiency anaemia seen in medical practice.(2)

*More than one factor is often present. † Role is unclear (limited available data show efficacy comparable to that of non-controlled-release formulations).
Pasricha SR, Flecknoe-Brown SC et al. Diagnosis and management of iron deficiency anaemia: a clinical update. Med J Aust 2010; 193(9): 525-532. © Copyright 2010. The Medical Journal of Australia - reproduced with permission.


  1. Pasricha SR, Flecknoe-Brown SC, Allen KJ, Gibson PR, McMahon LP, Olynyk JK, et al. Diagnosis and management of iron deficiency anaemia: a clinical update. MJA 2010;193:525–532. Available from:
  2. Camaschella C. Iron Deficiency Anemia. N Engl J Med 2015;372:1832-43. Available at:


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