Testing for PA after starting B12 tre... - Pernicious Anaemi...

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Testing for PA after starting B12 treatment


Are there any test that you can do to explain why you might be B12 deficient after you've been self-injecting for some time? My GP has finally accepted that my self-diagnosis might be correct as I am finally feeling so much better and is prepared to do more testing, but said I would need to stop all intake of B12 for 4 months for any tests to be accurate. I understand that is the case for testing active level of B12, but would it be the case too for testing for antibodies?

6 Replies
clivealiveForum Support

Hi Dizzinessloaded

A wiser person than I has posted this previously

"Taking supplements that contain B12 will affect any tests ordered by your doctor to assess your B12 status. You should not take any supplement with B12 before having your B12 assessed (including MMA/homocysteine/Active B12). For testing intrinsic factor antibodies: keep one week between an injection and the test".

I am not a medically trained pereson

Thank you very much Clive. I am prepared at this point to keep a week in between, but not physically and psychologically prepared to risk going back to where I was for too long, at least not yet.

I understand that intrinsic factors antibodies will confirm or dismiss a diagnosis of PA, is that correct? I've had high thyroid antibodies in the past (other thyroid tests normal) and am wondering if the two could be linked.

clivealiveForum Support in reply to Dizzinessloaded

Sadly the IFA test is unreliable in that it gives false negatives in people with PA half the time. So a negative result doesn't mean that you don't have PA. However, a positive result is a sure-fire, 95% certain indicator of PA.

Having thyroid problems may put you at risk of developing a B12 deficiency.

I wish you well.

Thanks again Clive. Part of me doesn't care that much about a diagnosis. Whatever the outcome, the treatment is the same. At the moment, I am just massively grateful to have find something that gives me a chance to feel a bit more like my old self.

Hi Dizzinessloaded,

I can't quote where you'll find this this documented (maybe someone else can?), but I understand that if you've had PA for a long time there may well be no IF antibodies in your body now. This is because once the antibodies have destroyed all of your IF then they're done, ie they are no longer required...nothing there to destroy any more so will no longer be active. This may explain why it's only 50% accurate.

This was the case with myself, the downside of having the test for me (IF neg) was that my GP then turned around and said "there you are - you don't have PA!" She then refused me any further B12....so it is a difficult area.

Wishing you all the best,


Thanks Drumstix. It seems that a lot of testing associated with Vit B12 is unreliable, probably why so many people are supposedly misdiagnosed with other conditions. I am quite happy to take control of my own treatment whilst keeping my GP informed. The only reason I can think of of wishing a firm diagnosis is work related, ie. I am considering reducing my hours at work, this would probably be denied for social reasons, but might not be if I could go via occupation health and evidencing my issues with chronic fatigue.

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