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Macrocytic or Megaloblastic Anaemia (Vitamin B12 Deficiency)



Anaemia with large red blood cells is commonly due to folate or vitamin B12 deficiency. Folate deficiency is common in pregnant women and in the postpartum period. Macrocytic anaemia in these women may be assumed to be due to folate deficiency and does not require further investigation (See Section 11.5.1 Anaemia in pregnancy. Vitamin B12 deficiency occurs mainly in middle-aged or older adults, and can cause neurological damage if not treated. Macrocytic anaemia outside of pregnancy or the postpartum period requires further investigations to establish the cause.

Risk Factors

Signs and symptoms

Diagnostic criteria

• FBC will confirm macrocytic anaemia.
• Elevated MCV
• White cell count and/or platelet count may also be reduced.
• If there is a poor response to folate, a serum vitamin B12 should be done.



  • Non-pharmacological

    Dietary advice:

    • Increase intake of folic acid rich foods such as:

    o Liver
    o Eggs
    o Fortified breakfast cereals
    o Citrus fruit
    o Spinach and other green egetables, lentils, dry beans, peanuts.

    • Reduce alcohol intake
    • Vitamin B12 deficiency anaemia: High protein diet is recommended (1.5 g/kg/day).
    • Increase intake of dietary vitamin B12 sources, including meat (especiallyliver), eggs and dairy products.
  • Pharmacological

    Folic acid deficiency:

    • Folic acid (PO) 5 mg daily until Hb is normal
    • Check Hb monthly

    Folic acid given to patients with vitamin B12 deficiency can mask the situation and eventually lead to neurological damage, unless vitamin B12 is also given.


Updated on,

20 Novemba 2020 10:08:02


    1. STG
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