microcytic anaemia

Last edited 05/2022 and last reviewed 05/2022

This is a type of anaemia where the mean cell volume (MCV) is less than 80 femtolitres (normal range = 80-100 fL).


The average erythrocyte is seen smaller than normal and much smaller than a leukocyte. Microcytic cells can appear to have a large area of central pallor.

The most common cause of microcytic anaemia is iron deficiency anaemia*. This shows a microcytic, hypochromic blood film with anisocytosis and poikilocytosis.

* NICE guidance states (2):

  • if iron-deficiency anaemia and aged 60 and over then refer people using a suspected cancer pathway referral (for an appointment within 2 weeks)
  • iron-deficiency anaemia (unexplained) with rectal bleeding in adults under 50 then consider a suspected cancer pathway referral (for an appointment within 2 weeks)
  • if iron-deficiency anaemia without rectal bleeding in adults under 60 then offer testing for occult blood in faeces (FIT)


Note that reference ranges may vary between laboratories.


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