The Need for Better Antibody Tests

I have to start with a long story but I will eventually get to the point so please bear with me.

In 2010 I was tested for celiac disease. The tests run were TT IgA, Gliadin IgA, Gliadin IgG, Reticulin IgA Autoabs, and Endomysial IgA Autoabs. The *only* test that came back positive in that group was the Gliadin IgA. Given that the test was run in 2010, I am certain it was the AGA version. That version of the test is no longer performed. I found this footnote at the bottom of a labtestsonline page:

"Historically, a test for anti-gliadin antibody (AGA) was used in the evaluation of celiac disease. The 2013 American College of Gastroenterology guidelines recommend against this test for the primary detection of celiac disease due to concerns with its accuracy. It is inferior to the tests for anti-tTG and anti-DPG and should no longer be part of routine testing for celiac disease. The American Gastroenterology Association makes similar recommendations."


The phrase 'concerns with its accuracy' does nothing to tell me whether the test skewed more toward false positives or false negatives so I looked a little bit more and found this article which actually lists percentages:

According to this article, the AGA IgA test had a 72% accuracy rate.

Do you realize that the Intrinsic Factor antibody test, which is the only test that can specifically diagnose Pernicious Anemia, has only a 60% accuracy rate?

I can't help but be irate that the medical establishment has seen fit to discontinue (and actually replace) the AGA Iga test, but is still completely reliant upon the IF antibody test which misses *almost half* of the people who have PA.

What does it take to get a better test developed and put into practice? Is there something to be learned from the process that resulted in replacing the AGA test?

As frustrating as it is to know that a terribly inaccurate test is all that is currently available, at least it is apparent that tests can sometimes be improved upon and replaced. I hope we can get a more accurate Pernicious Anemia test widely available someday.

11 Replies

  • Very interesting- I have no idea why it is so poor and has not been improved upon and the other more accurate test has also been done away with- Schilling test- I think because of the use of radioactivity and pork intrinsic factor. Woeful.

  • Yes, I think those are exactly the reasons the Schilling test was discontinued. There may be one or two labs somewhere that are still willing to perform it, but most don't.

  • Yes, most of us will be aware of just how unreliable the IF test is, and the IFA, and the Anti Parietal test, and the b12 serum test itself doesn't tell us just how much is usable. Before any supplementation is done, an MMA (methylmalonic acid) test and Plasma Homocysteine test would be far more reliable, both are elevated when a body is short of B12. But once supplementation is started these tests are just as unreliable as the others. Not great, eh?

    However, doctors are SUPPOSED to use the clinical presentation and NOT rely on blood tests anyway.

  • Doctors aren't supposed to ignore blood test results but they are supposed to look at the whole picture. Sadly many doctors use blood test results to refute the clinical presentation instead of realizing that blood tests are not perfect. Some doctors even seem to think that they get to choose whether or not the given reference range matters.

    I'm just sick of being in perpetual limbo. I'm fairly certain that I fall into the 40% of people who have PA but don't test positive for IF antibodies. But just because I feel that is the case doesn't mean any doctors will agree with me.

    (I was diagnosed with PA in 2008 when I tested positive for parietal cell antibodies and then un-diagnosed a year later when I tested negative for both parietal cell and intrinsic factor antibodies.)

    Being in limbo about the gliadin IgA test also is just another frustration to add to the list. :(

  • "Some doctors even seem to think that they get to choose whether or not the given reference range matters"

    Oh, how I sympathise with that one, Galixie. My doctor loves to move the goalposts; he just can't get enough of it. Just as one example, I have neutropenia, caused/exacerbated by Carbamazepine. When I was discussing the fact that my white blood cells were steadily dropping at every blood test he quickly rejoindered, "Yes, but you had neutropenia before you went on Carbamazepine". In other words, the Carbamazepine isn't having any effect. He knows that's HIGHLY unlikely, since Carbamazepine is known to effect white blood cell counts, ESPECIALLY in people with existing neutropenia, but suddenly this was being used against me because it suited him. I guarantee if I had been arguing about my neutropenia being a pre-existing condition he'd have said, "But Carbamazepine is known to effect white blood cells". He does this EVERY time, rendering any discussion I try to have with him an exercise in frustration. Literally anything on the blood tests will be used to argue for AND against the same thing as it suits him.

    I have had endless arguments with him about coeliac testing because I have partial IgA deficiency. This is actually marked as low on my blood tests, but when I tried to get retested, taking this into account, suddenly it wasn't low enough. Apparently there is low and authentic low and only they can decide which low is genuine or important. Kind of defeats highlighting it on the blood tests.

    It amuses me that they think bodies work like identikit pictures. When I tried to discuss my 'grey zone' B12 with him (384) he wouldn't hear that there can be a range at which some people are affected and others not. When, later still, B12 injections proved to 'heal' the (very serious) problem we had been fighting over, it STILL wasn't the B12, it was "placebo" and "a coincidence". He still believes that, which makes me the longest running placebo effect patient in the world, ever, I reckon.

    What mystifies me is what it's all ABOUT. Why do it? Why keep arguing over futile stupidities? It feels like some kind of ego thing, but I've yet to work out the true point of it.

    And thanks for putting the IF inaccuracy into perspective. I had never really grasped just how poor that accuracy was before. I feel the same is true of coeliac testing. I'm still not convinced I don't have a gluten issue, despite being found repeatedly negative for all the tests. But I keep telling my doc that I believe my gluten problem is neurological, not gastric, and these tests are all gastric-centred, but he won't shift. He doesn't believe in it, the NHS doesn't test for it, therefore it's not happening. I really have no idea how to fight that....

  • Hi I empathise. I was told by a neurologist that my dramatic improvement on alternate day injections including a change in physical signs was a "coincidence" and he accounted for going from no vibration sense in my feet discovered by one doctor at the beginning to him finding that I had regained vibration sense in my feet after treatment as him having"better technique"!!!

  • Good lord, that does take the biscuit, secondchance - not only are you suffering from the dreaded 'everything you say I can negate with the word coincidence' but any healing you DO have is all down to his "better technique". In what? Being an ass?

    Do you see what I mean though? There definitely seems to be some kind of ego involved here, doesn't there? Did their mothers not praise them enough or something?

  • Yes he was very dismissive. He basically ignored anything my husband said about my improvement too. Nothing relevant to B12 went in his letter either apart from the coincidence! Yes I think he was an expert in that particular technique!

  • Ah, bless. Well, never mind, some day they might be sick and struggling and we can only hope some of that karma comes back to get them!

  • It sounds like there is a need to get some reliable testing for most symptoms which point in a particular direction. Most tests don't have a very good sensitivity rate and because the body has many organs that rely on one another it makes diagnosing really difficult unless you are categorically and most definitely within a particular disease groupds and your blood test prove that categorically without question.

    If you for any reason are showing normal bloods but possibly have got a problem with the need for further investigation you really do have a hard job to get the right diagnosis.

  • I feel all of you, and me too, have every right to complain about poor quality of tests used and relied upon, about ranges that differ wildly wherever you have the fortune or misfortune to live, and to complain about the lack of understanding amongst friends family and employers. But none of that, NONE of it would matter if doctors would at least treat according to the guidelines, and to my mind it doesnt matter a hoot if i have PA or B12def, I simply what my nasty life threatening symptoms treated!

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