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  • The Review Course in Family Medicine

The B12 Breakdown - 5 Tips to Navigate B12 Deficiency in Your Patients

Here are five essential tips to help you navigate and manage B12 deficiency effectively in your clinical practice.

1. Be attentive to possible B12 deficiency in your elderly patients.

2. Consider deficiency in those with neuropsychiatric findings, neuropathies or hematological abnormalities especially macrocytic anemia.

3. A deficiency is measured with a plasma level < 148pmol/L but some may have symptoms at a marginal deficiency level of up to 221pmol/L.

4. Common causes include autoimmune gastritis, vegan/vegetarian diets and malabsorptive states. Remember iatrogenic causes like post-gastrointestinal surgery or medications like metformin and proton-pump inhibitors (PPIs).

5. High dose daily oral supplementation (1000 mcg) is as effective as intramuscular (IM) injections.

Hematological abnormalities will resolve within weeks but it can take months for neuropsychiatric symptoms to improve.

With knowledge of these strategies, you can play a pivotal role in identifying and addressing B12 deficiency in your patients, ultimately promoting their overall health and well-being. For a deeper understanding, refer to the references below.


Vitamin B12 deficiency

William K. Silverstein, Matthew C. Cheung and Yulia Lin

CMAJ June 20, 2022 194 (24) E843; DOI:



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