Vitamin B12 deficiency


Metformin B12 malabsorbtion - It has been suggested that an increased intake of calcium reverses the vitamin b12 Malabsorption induced by metformin.

Serum vitamin B12 WITH neurological symptoms  


Serum vitamin B12 WITHOUT neurological symptoms 


  • levels should always be checked in vitamin B12 deficient patients
  • If low levels are found prescribe folic acid 5 mg tablets daily
  • Usually, treatment will be required for 4 months, however, folic acid may need to be taken for longer (sometimes for life) if the underlying cause of deficiency is persistent

Neurological symptoms 

  • Partial or complete paralysis
  • Muscle weakness
  • Unexplained pain
  • Pins and needles (parathesia)
  • Partial or complete loss of sensation
  • damage to parts of the nervous system (peripheral neuropathy); particularly in the legs
  • Seizures
  • Vision problems
  • Memory loss
  • loss of physical co-ordination (ataxia), which can affect whole body and cause difficulty speaking or walking
  • Difficulty reading and writing
  • Poor cognitive abilities
  • Decreased alertness

Dietary sources

Vitamin B12

  • Eggs
  • Foods which have been fortified with vitamin B12 (for example some soy products, and some breakfast cereals and breads) are good alternative sources to meat, eggs, and dairy products
  • Meat
  • Milk and other dairy products
  • Salmon and cod

Folic acid  

  • Asparagus
  • Broccoli
  • Brown rice
  • Brussels sprouts
  • Chickpeas
  • Peas


  • Perform a full blood count and reticulocyte count:
    • Within 7–10 days of starting treatment
      • A rise in the haemoglobin level and an increase in the reticulocyte count to above the normal range indicates that treatment is having a positive effect
      • If there is no improvement, check serum folate level (if this has not been done already)
    • After 8 weeks of treatment, and also measure iron and folate levels
      • The mean cell volume (MCV) should have normalised
    • On completion of folic acid treatment to confirm a response
  • Measuring cobalamin levels is unhelpful as levels increase with treatment regardless of how effective it is, and retesting is not usually required
    • However, cobalamin can be measured 1–2 months after starting treatment if there is no response
  • Neurological recovery may take some time — improvement begins within one week and complete resolution usually occurs between six weeks and three months
  • Ongoing monitoring is unnecessary unless a lack of compliance with treatment is suspected, anaemia recurs, or neurological symptoms do not improve or progress

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