Determination of underlying cause

Factors to consider when investigating the underlying causes of iron deficiency anaemia (IDA)

  • iron deficiency anaemia should be confirmed (see Diagnosis and investigation of IDA)
    • the lower the haemoglobin, the more likely there is to be serious underlying pathology and the more urgent the need for investigation (B)*
  • management consists of two concurrent components
    • iron therapy to normalise haemoglobin and replenish stores (B)*; and
    • determination and treatment of underlying cause
  • all patients should be screened for coeliac disease (B)*
  • causes of IDA may be multifactorial
  • history, examination, age and gender will guide investigations (see below)
  • faecal occult blood testing is of no benefit in the investigation of IDA (B)*
  • blood loss from the gastrointestinal (GI) tract is most common cause of IDA in adult males and postmenopausal females
  • upper and lower GI investigations should be considered in all postmenopausal female and all male patients where IDA has been confirmed unless there is a history of significant overt non-GI blood loss(A)†
  • young males should be investigated in the same manner as older males (C)**, although it is reasonable to avoid investigations where there is an obvious cause of blood loss (eg, blood donation) unless anaemia recurs despite correction of the cause of blood loss
  • menstrual blood loss is the most common cause of IDA in premenopausal females; increased demands of pregnancy and breastfeeding also contribute
  • consider other causes of blood loss (including blood donation) and/or inadequate iron intake
  • colonic investigation in premenopausal women should be reserved for those with colonic symptoms, a strong family history (two affected first-degree relatives or just one first-degree relative affected before the age of 50), or persistent IDA after iron supplementation and correction of potential causes
  • iron deficiency without anaemia is three times as common as IDA
  • the British Society of Gastroenterology guidelines state that “there is no consensus on whether these patients should be investigated”; and tentatively recommend:
    • coeliac serology in all patients
    • reserving other investigation for those with high risk profiles (eg, age >50 years) after discussion of the risks and potential benefits of upper and lower GI investigation (C)**
    • treating all others empirically with oral iron replacement for 3 months and investigation if iron deficiency recurs within next 12 months (C)**
Levels of evidence

*Level B evidence - British Society of Gastroenterology Guidelines for the management of iron deficiency anaemia, 2011

†Level A evidence - British Society of Gastroenterology Guidelines for the management of iron deficiency anaemia, 2011

** Level C evidence - British Society of Gastroenterology Guidelines for the management of iron deficiency anaemia, 2011

Further information and guidance
  1. Gastroenterological Society of Australia. Clinical update: Iron deficiency, Updated 2015. Sydney, Australia, Digestive Health Foundation, 2015. Available from:
  2. 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:
  3. Goddard AF, James MW, McIntyre AS, Scott BB on behalf of the British Society of GastroenterologyGuidelines for the management of iron deficiency anaemia. Gut 2011;60:1309–1316. Available from:


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