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Megaloblastic Anemia


This is a condition whereby the bone marrow usually produces large, structurally abnormal, immature red blood cells (megaloblasts) often due to inadequate intake or malabsorption of vitamin B12 or folate.


Diagnostic Criteria

Pallor, depression, hair loss, pins and needles, numbness in hands or feet, tremors and palsies, mildly jaundiced (lemon yellow tint), beefy tongue, darkening of palms and ataxic gait.



  • FBC-Low Hb, sometime pancytopenia, raised mcv but maybe low normal if coexisting with iron deficiency 

  • Peripheral smear-oval macrocytes, hyper segmented neutrophils

  • Serum vitamin B12 maybe low or normal, Serum folate level, TSH, U+Es, LFT

  • Raised reticulocyte count

  • Bone marrow studies may be indicated 

Pharmacological Treatment

  • Vitamin (B12 deficiency anaemia) and other macrocytic without neurological involvement

  • Hydroxycobalamine, initially 1 mg IM 3 times a week for 2 weeks then 1mg every 3months 

  • Clinically review every 2 months with or without serum B12 and if clinically indicated increase the frequency to every 2 months or every month 

  • Pernicious Anaemia (B12 deficiency) with neurological symptoms and signs  

  • Hydroxycobalamine, initially 1 mg IM on alternate days until no further improvement (maximum reversal or neuro-psychiatric signs and symptoms are achieved) then 1mg every 2 months 


Folic acid 5mg (PO) once daily for least 2 months this must be started simultaneously with injection vitamin B12

 Ferrous Sulphate 200mg 8 hourly for at least 3 months 

Updated on, 27.10.2020


1. STG page number 18-19

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