Intrinsic Factor Antibody Test - What a Mess!

Okay, so we already know that the IFA test is only 50% reliable. That means it will only pick up 50% of people who have the antibodies. Anybody else can go jump in a lake.

Now we have this:

"Do not order intrinsic factor blocking antibody (IFBA) testing in patients who have received a vitamin B12 injection within the last 2 weeks. High free serum vitamin B12 levels, as may be seen within the first 2 weeks after a vitamin B12 injection, can interfere in the IFBA assay, leading to false-positive results. We reflex all positive IFBA tests that have not been ordered through the Pernicious Anemia Cascade to vitamin B12 measurement. If this yields a level >800 ng/L, we append a comment to the report indicating a possible false-positive result.

Some patients with other autoimmune diseases may have positive IFBA assays without suffering from pernicious anemia (PA). This is reported inparticular in patients with autoimmune thyroid disease or type I diabetes mellitus. In the validation of this assay, "

mayomedicallaboratories.com...

This means that anyone who had a B12 injection within the 2 weeks before having an IFA test most likely gave a false positive result. ie They do not have PA. It also says the same stands for people who have autoimmune thyroid.

So trying to sort this mess out (and I'm excluding here the mess associated with parietal cell antibodies) we have a situation where they are using a test which is only 50% accurate, can throw up a false positive result in the remaining 50% if they had B12 for the 2 weeks prior to the test, or they have autoimmune thyroid or type 1 diabetes.

This, of course, is based on the assumption that they are chasing the right thing - ie an anaemia - which has been proved not to be the case - and that low B12 don't really matter....

And, of course, this is now all occuring because for some strange reason it has been decided that B12 deficiency is only important if it can be diagnosed as an auto immune condition - whereas the biochemistry states that it is the lack of b12, for whatever reason, which causes neurological and psychological damage.

How sad that we rely on such unreliable science instead of physical evidence from the patients.

8 Replies

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  • Yeah the false positive thing happened to me, I ended up having 3 IF tests, 2 negative and 1 positive a few hours after an injection. Just get the test done and you can also get a gpc test done as well, if you are positive in either of these and its a good few weeks after your injection then you can presume you have PA. You can also presume you have it if you do need the injections for life, you may just have to keep getting injections and measuring your b12 and see how it go's.

  • So what happens if you have low stomach acid which is said to be caused by antibodies but don't have positive antibody tests?

    And what is it that is important about the autoimmune that causes the neurological or cellular damage which is specific to a diagnosis of PA?

  • I'm not sure neurological damage is specific to PA, I thought that was just due to having a b12 deficiency whatever the cause may be but its probably worse with PA because you are literally absorbing no b12 all the time. I didn't actually know that IFab causes low stomach acid. You'll find that a lot of people get put on b12 injections and they don't actually know why, sometimes it can be very difficult to analyse what is causing the deficiency and most drs just find it easiest to just put you on the injections and leave it at that. If you have any gastric/digestive symptoms and a b12 deficiency then you should be referred to a gastroenterologist for further testing, they may be able to see whether you have low stomach acid.

  • I've had a test for low stomach acid, which I paid for privately and I know I've got it.

    Most people don't have the pH tested because there is only one test in the US (Heidelberg) and none in Europe which are recognised.

    With regard to PA - the goal posts just keep moving. When I first came to the forum PA was about lack of IF. Not testing postitive for autoimmune. Lack of IF meant b12 couldn't be transported - end of story. Now they are saying that it has to be a lack of IF caused by autoimmune. Well, what difference does that make - it's the lack of B12 that's the problem and if you a) aren't producing it, or, b) can't transport it, then you've got a problem.

    On top of that of course we have the complete unreliability of the tests - all of them related to this illness.

    There are so many people who have B12 deficiency but the cause remains unidentified - yet the presumption is, now, that because they haven't tested positive for antibodies then they somehow 'can' produce and transport B12 - which is a nonsense.

    I tell you - it's a mess.

  • It is a mess, it doesn't help that GP's know so little on the subject. From what I'm aware IF is produced by gpc's and helps break down vitamin b12 to something that can be absorbed. PA is autoimmune which is when your body creates antibodies that either attack the IF so very little b12 can become absorbed or your body creates antibodies that attack the GPC so that they can't produce IF anymore. I suppose it depends what PA is classed as, whether its just the autoimmune cause due to damaged IF or GPC or whether its just if you seem to need injections for the rest of your life for whatever reason. Your right it is a mess! I still don't know what's causing mine. My GP said that I should should presume I have PA because b12 injections helped and I have a family history of autoimmunes.

  • Well, you're a little bit wrong in that IF breaks down the B12 (at least I think you are) because it is just a transport protein. Even then it doesn't transport it from the stomach but from the upper intestine. But everything has got muddled up - and that isn't helped by the fact that doctors think B12 deficiency causes only a blood condition and the neurological problems follow. Which isn't necessarily the case. So, they don't think it's important anyway!

    When it comes to causation nobody seems to mind that the presumption is made that you need (now) to be diagnosed with autoimmune for it to be important. The simple fact remains is that if a patient isn't absorbing B12 then the metabolic functions it performs, can't be. And that's why many have the neurological symptoms.

    Yet some doctors treat the symptoms as cognitive, others dismiss completely, some people get diagnosed with something else and get a bucketload of meds they also can't absorb.

    Then the researchers are looking into autoimmune, they are concentrating on IF - and the B12 thing gets completely swept under the carpet.

    We can just hang around for years waiting for them to get their act together and start understanding the metabolic processess of B12, and the impact on digestive function and the fact that all patients need differing levels of medication.

    No problem - we can wait!!!

  • 'you should EB referred to a Castroenter I locust...." This seems to be important - could you correct and repost please?

  • I think I wrote this on my phone and it has a crazy auto correct, I didn't even notice! I meant that if you have a B12 deficiency and any gastric/digestive symptoms then you should be referred to a gastroenterologist to have more investigations done.

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