Best test for determining B12 deficiency/PA?

Hi there everyone

I'm finding it difficult to get B12 deficiency as investigated by my GP, here's my recent serum tests results:

VITAMIN B12: 186 pmol/L 140.00 - 724.00

I want to just get some private tests done as I'm running out of patience but as tests are a bit pricey I'm looking for the best test to get. From what I've read MMA seems to be the one most people would suggest. Do you all agree? And is a urine one as good as a blood one?


4 Replies

  • MMA in urine is actually preferable to MMA in serum because it is easier to interpret as markers of other conditions that can cause MMA to be raised are clearer in the Urine test.

  • Thank you again Gambit!

    So would you say MMA is a better route to go down than, say, Intrinsic Factor?

  • IFA looks at one potential cause of a B12 deficiency - and yes you should look into what the cause is - but as it's prone to give false negatives 40-60% of the time a negative result doesn't actually rule out PA so its a bit of a problematic test.

    There are other conditions and a lot of drug interactions that can cause a B12 deficiency.

  • Hi,

    Are you in UK?

    Links about testing for B12 deficiency

    Are you symptomatic for B12 deficiency?

    pernicious-anaemia-society.... see checklist

    In UK patients who are symptomatic for B12 deficiency are supposed to have an IFA(intrimsic factor antibody) test and start initial b12 treatment. See flowchart from BSH Cobalamin and Folate guidelines below. IFA test can help to diagnose PA but is not always reliable. It is still possible to have PA if IFA test is negative (called Antibody Negative PA).

    Other b12 info

    1) BMJ B12 article

    2) BNF Chapter 9 Section 1.2

    3) Book "What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

    4) Book "Could It be B12" by Sally Pacholok and JJ. Stuart

    5) pinned posts on this forum

    I am not a medic just a person who has struggled to get a diagnosis.

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