Microcytic anaemia is defined as a mean cell volume < 80 fL and haemoglobin levels below what would be normal for a person’s age and sex
The most frequent cause of microcytic anaemia is iron deficiency
The cause of iron deficiency anaemia always needs to be investigated, some of the primary causes are: obstetric/gynaecological (e.g. menorrhagia or pregnancy), gastrointestinal bleeding, malabsorption (e.g. coeliac disease), medicines that cause gastric erosions/ulcerations and those that interfere with coagulation/platelet function, dietary deficiency (e.g. vegans), or other reasons (e.g. blood donation, trauma, surgery)
Treating iron deficiency anaemia:
If appropriate, prevent further blood loss by treating the underlying cause, e.g. reduce menstrual loss in premenopausal women
Review and correct any dietary factors; patients diagnosed with coeliac disease should begin a gluten free diet
Patients with uncomplicated iron deficiency can be given a trial treatment with oral iron supplementation to correct anaemia and replenish physiological stores
Ferritin should be used to investigate suspected iron deficiency anaemia
Serum ferritin alone is a highly sensitive test of iron deficiency in patients with otherwise good health. Iron studies (serum iron, iron binding capacity and serum transferrin) should not be ordered as initial first-line tests.
Iron studies may be indicated if iron overload is suspected, or other comorbidities are known or suspected. If serum ferritin is increased (iron deficiency is unlikely with ferritin levels over 100 micrograms/L), iron studies may be requested for further investigation.