Iron Deficiency Anaemia
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Iron deficiency anaemia (IDA) is the most common cause of anaemia world-wide. It occurs when there is insufficient iron to facilitate red blood cell production. It is particularly important in the developing world as a cause of poor development in children.

It typically produces a microcytic anaemia, of which iron-deficiency anaemia is the most common type. Anaemia of chronic disease is the other main cause of microcytic anaemia, and it is also seen in thalassaemia and rarely – lead poisoning.

Anaemia in general is defined as haemoglobin (Hb) less than:

  • 130 g/L in men
  • 120 g/L in women
  • 110 g/L in pregnant women and children
  • Note that some centres use the unit g/dL, which result in a number 10x lower:
    • 13 g/dL¬†in men
    • 12 g/dL in women
    • 11 g/dL in pregnant women and children <12


  • Affects 2-5% of the population world-wide
    • More common in menstruating females – up to 20%
  • Most common cause of anaemia in pregnancy – which can have detrimental effects to both mother and foetus



  • Dietary deficiency (inadequate intake, veganism / vegetarianism makes iron deficiency more likely but green vegetables re a good source and a proper vegetarian diet should not cause deficiency)
    • More common in children (picky eaters) and the elderly
  • Coeliac disease
  • Post-gastrectomy
  • Pica – ingestion of none-food items – e.g. dirt

Drugs can lead to malabsorption through various mechanisms:

  • PPI – reduces absorption due to increased gastric pH
  • Tetracyclines and quinolone bind to iron and reduce absorption

Blood loss

If often “occult” (not seen) and originating from the gastrointestinal tract. Any cause of blood loss can lead to iron deficiency anaemia. Some of the more common reasons include:

Increased physiological requirements

  • Pregnancy
  • Infancy


Anaemia may often not be an obvious diagnosis. Be wary of this as a cause of symptoms in anyone with an aggravation of angina, heart failure or claudication. Many cases also present with non-specific symptoms of tiredness.

Symptoms can include:

  • Tiredness or fatigue
  • Headaches
  • Muscle aches or weakness (without true neurological weakness)
  • SOBOE (shortness of breath on exertion)
  • Palpitations
  • Angina
  • Intermittent claudication
  • Hair loss

Signs may be non-specific but can include general signs of anaemia:

  • Pallor (paleness) of tongue, nail and conjunctiva (unreliable signs)
  • Tachycardia
  • Systolic (pulmonary) flow murmur
  • Signs of heart failure (if severe)
  • Jaundice – seen in haemolytic anaemias

Specific to iron deficiency:

  • Angular stomatitis
  • Glossitis (inflamed tongue), and taste disturbance
  • Brittle nails
  • Koilonychia – spoon shaped nails – late sign of severe iron deficiency anaemia
  • Hair loss


A combination of FBC (full blood count) and iron studies is required to make the diagnosis.

Actual serum iron levels are often not particularly useful Рprone is an acute phase reactant and levels increase with acute inflammation, and thus are very variable. Serum ferritin is a much more reliable marker. Transferrin is also physiologically raised in pgrenancy

Iron deficiency anaemia
Serum Iron
TIBC (Total iron binding capacity) ‚Äď sometimes called Transferrin
Serum Ferritin
Transferrin saturation

Once a diagnosis of iron deficiency is made, then further investigation for the underlying cause is necessary:

  • Screen for coeliac disease (all patients)
  • Consider endoscopy (upper and lower) in men and post-menopausal women, if any concerning features
  • Consider H. pylori testing
  • In the over 50s consider endoscopy in patents with iron deficiency even without anaemia

Be particularly more concerned for a sinister cause in patients who are unable to maintain normal iron levels despite supplementation.

Appearance of red blood cells on blood film in iron deficiency anaemia. Note the irregular shaped blood cells that appear hollow. The white cell in this picture is normal.
Appearance of red blood cells on blood film in iron deficiency anaemia. Note the irregular shaped blood cells that appear hollow. The white cell in this picture is normal.

Differential Diagnoses


Usually involved treating the underlying cause.

  • Dietary factors – encourage foods high in iron, such as:
    • Legumes
    • Red meat – beef, veal, port, liver, poultry
    • Green vegetables – spinach, lettuce, silver beet
    • Pumpkin and sweet potato
    • Seafood – oysters, sardines, tuna
    • Seeds – sesame and pumpkin
    • Eggs – especially egg yolk
    • Fresh fruit
    • Also encourage foods high in vitamin C – as this aids the absorption of iron
      • Citrus flirts, brussels sprouts, broccoli, cauliflower
    • Limit milk intake to <500mls per day
    • Bread is often fortified with iron in developed countries
  • Iron supplements
    • Many brans available
    • Ferrous sulphate and ferrous fumarate are the two active ingredients
      • There is thought to be minimal difference in absorption, although side effects may be variable
    • Usually tablets have a dose of around 200-300mg
    • Take 1-2 tabs daily
    • Advise to take with a glass of orange juice
    • Commonly cause GI side effects
      • Constipation or diarrhoea
      • Dark stools
      • Dyspepsia (heartburn)
      • Nausea
      • Abdominal pain
  • Iron infusion
    • Can be used in severe cases, or those who have failed oral supplementation
    • Beware that iron infusion can cause¬†permanent¬†staining of the skin around and proximal to the cannula site (usually if the cannula “tissues”) – which has been a source of litigation against medical practitioners
    • Avoid blood transfusion unless severe symptomatic anaemia
  • Consider contraceptive methods that rescue menorrhagia in women suffering from this

Re-check FBC 2-4 weeks after initiating treatment

  • Then every 3 months for 1 year
  • Then again after another year

If blood results are not improving:

  • Check compliance and treat any side effects (e.g. laxatives for constipation), or adjust the dose. Reassure black stools are normal and harmless

When to refer

  • Anaemia with heart failure – consider urgent referral to hospital
  • Women with menorrhagia where the menorrhagia is unresponsive to treatment – refer to gynaecology
  • If uncertainty about the type of anaemia – consider referral to haematology
  • Men or post-menopausal women without an obvious cause, or not responding to oral therapy – refer to gastroenterology for urgent endoscopy
    • Men of any age with Hb <110 g/L need urgent referral for endoscopy
  • Consider referral to dietician if diet is believed to be an important contributing factor


  • Iron-deficiency Anaemia –
  • Murtagh‚Äôs General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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