Determining the underlying causes

Current evidence-based clinical guidelines highlight the following factors to consider when investigating the underlying causes of iron deficiency anaemia (IDA).


All patients

  • Iron deficiency anaemia should be confirmed (see Diagnosis and investigation of IDA).
  • Management consists of two concurrent components:
    • iron therapy to normalise haemoglobin and replenish iron stores; and
    • determination and treatment of underlying cause.
  • History, examination, age and gender will guide investigations (see below).
  • Causes of IDA may be multifactorial.
  • All patients should have urinalysis or urine microscopy and be screened for coeliac disease.
  • There are currently insufficient grounds to recommend faecal occult blood testing or risk stratification in patients with IDA.


Males and post-menopausal females

  • Blood loss from the gastrointestinal (GI) tract is most common cause of IDA in adult males and postmenopausal females.
  • Gastroscopy and colonoscopy should generally be the first line GI investigations in men and postmenopausal women with newly diagnosed IDA.
  • Confirmed IDA is uncommon in young men but when found, the British Society of Gastroenterology recommend that it warrants the same investigational algorithm as for older people.


Premenopausal females

  • IDA is common in young women, and major contributory factors include menstrual losses, pregnancy and poor dietary intake.
  • Underlying GI pathology is uncommon in young women with IDA, and after screening for coeliac disease, the British Society of Gastroenterology recommend that further investigation is warranted only if there are additional clinical features of concern such as, age over 50, non-menstruating (e.g. hysterectomy), red flag GI symptoms, major genetic risk (e.g. for colon cancer, two affected first-degree relatives or one first-degree relative affected before the age of 50), or recurrent or persistent IDA after iron supplementation and correction of potential causes.