BCSH | Vitamin B12 and folate deficiency

12th June 2014 by Louise Hudman

BCSH | Vitamin B12 and folate deficiency

This is a new guideline from the BCSH. It is quite a chunky guideline and it covers a lot of detail. I will give a few ‘top learning points’ then a more detailed summary beneath. At the end I have attached some algorithms, which are really helpful in knowing how to investigate / manage people.

Top learning points

How good is the test?

There is a lot of inter-lab variation. Using a cut-off of 148 pmol/L (200 ng/L) it has a sensitivity of 97% – so pretty good in that sense. However, some assays are affected by high anti-intrinsic factor antibody (IFAB) and can give a false normal result. If there is folate deficiency, you can also sometimes get a false normal result.

What should you do on looking at any B12 result?

What is the clinical scenario? If there was a high degree of suspicion (eg megaloblastic anaemia, neurological symptoms, glossitis), then you may not trust a ‘normal’ result and you may want to look further.

What tests should you do looking for the cause of the B12 deficiency?

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