Last reviewed 09/2022

The diagnosis of folate deficiency anaemia is made by:

  • clinical picture
    • often the cause is dietary - may be associated with other factors such as chronic disease, alcoholism, pregnancy
    • other causes include malabsorption, drugs, excessive utilisation of folate in malignancy, chronic well-compensated haemolysis (this may even occur with a normal haemoglobin level)
    • take a detailed history - consider causes noted above - diet, drugs, alcohol, symptoms of malabsorption
  • diagnosis of megaloblastic anaemia:
    • FBC - macrocytic anaemia
    • a thrombocytopaenia may occur secondary to ineffective megakaryopoiesis
    • blood film - macrocytosis, hypersegmented neutrophils
    • bone marrow - megaloblastic erythropoiesis, giant metamyelocytes
  • measurement of red cell folate levels; a good index of long term status as opposed to plasma folate levels which indicate recent nutritional status
  • also measure serum B12 levels and absorption - the other main cause of megaloblastic macrocytic anaemia
  • anti-gliadin and anti-endomysial antibodies - this may reveal subclinical coeliac disease
  • liver function tests other haematinics - if not already undertaken - a useful assessment of nutritional status