IF Antibody test False Positive?

Diagnosed with PA from low B12 and positive IF Antibody test a few years ago. Had lots of trouble getting injections until I taught myself by watching YouTube. Was injecting weekly for just over 2 years.

About 18 months ago, lost the courage to SI. Just couldn't bring myself to stick the needle in and push the plunger. Apart from regaining appetite, the injections did very little in terms of improving symptoms.

Around the same time as stopping injections, replaced a 40+ years smoking habit with vaping. Was going through 3 packs a day. Recently realized, stopping smoking has reduced more symptoms than years of injections and all the other medicines ever did.

From a recent blood test, B12 and all other levels are fine. Told doctor no injection or other medication for over a year, he just smiled. Don't think he believed me because the hard facts, the test results, say differently (if really have PA).

So, whats the odds the initial IF antibody test was a false positive? Could smoking have effected the results?

OR, has my body stored all that B12 I injected and one day in the future I'll come crashing down when it finally runs out?

6 Replies

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  • Are you in the UK tflynnhk?

    "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".

    I'm not a medically trained person but have had P.A. for more than 45 years.

  • Not in the UK, live in an asian country

  • the symptoms of B12 deficiency overlap with a number of other conditions so it may be that B12 absorption isn't a problem.

    A false positive is possible if you have supplemented or had an injection very recently when the sample is taken - how recent depends on the exact test method - and varies between about 10 days and 24 hours.

  • The results are in. Stored b12 is depleted, crashing rather fast. Started a couple of days.

    From an objective viewpoint, 2 years of weekly injections equates to 20 months before re-onset of symptoms.

    This may be useful for someone to convince doctor to increase frequency of injections. Preparing for the unexpected... the more frequent the injections, the more excess B12 stored in liver, the longer you can go without needing an injection.

  • In your post you mention that other than regaining your appetite b12 did very little to improve your symptoms.

    Just want to give friendly reminder that b12 only works in the presence of its cifactors: folate and iron.

    Additionally, tests for these nutrients can be well within range initially but can be depleted rapidly once injections begin. Therefore it can seem and actually be that the b12 injections aren't helping much.

    Best of luck

  • Supplementing with B12 doesn't increase the body's requirements for folate or iron above that required normally.

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