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Pernicious Anaemia Society
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Some questions about Pernicious Anaemia and the causes of B12 deficencies?

I've been given very little information on PA by my doctors and they have only just tested me for PA even though I have had borderline low b12 for over a year (I'm currently waiting for the results). I'm a 19 year old female and the doctors seem to be really reluctant to see whether I had PA or not and I don't understand why. I have a family history of coeliac disease and hypothyroidism for which I am negative for both, I even had an endoscopy for coeliac disease. So what else could possibly be causing my low b12? I have a very healthy diet with fish, diary and meat yet my GP says the most common cause of b12 deficiency for her is poor diet and its likely that I'm just someone who needs more b12 than others... Could that by right?

My other questions are:

-Do you have to be anaemic to have PA? I have never been anaemic.

-I have already had a test for gastric parietal cells and it was normal, could I still have PA?

-I was only ever borderline low around 148 (ref 150-1000) could it still be PA?

-I got tested for PA 2 hours after my first b12 injection, is it likely to disrupt the test? They are doing an IF test and the dr and specialist nurse seemed to say that it should be okay...

If you can answer just one of these questions it would be great


7 Replies

1. No. The name Pernicious Anaemia is misleading. You can have serious B12 deficiency without ever showing signs of anaemia.

2. Yes. The gastric parietal cell and intrinsic factor antibody tests are unreliable.

3. 148 only looks borderline because of the ridiculous "normal" range used in the UK. In some countries anything below 500 is considered low. The blood serum test (which is the one you will have had) is unreliable anyway as it measures total B12 without taking into account that B12 is present in the blood in both active and inactive forms. There is a more reliable test known as the Active B12 test which can be done privately but for this to be accurate you would have to stop injections for several months.

4. Yes. I presume what you refer to as the PA test will be the intrinsic factor antibody test. This is never very reliable and will be made more unreliable by the injection 2 hours previously.


Thanks for the reply :) Its annoying that we seem to have such large reference ranges here in the UK


Hi Carly,

Firstly welcome and perhaps you just have to accept you have a problem absorbing B12, why may never come to light. Both my Daughters where diagnosed B12 def in late teens early twenties, my gran mother was diagnosed in early twenties, I am, my father, two of his sisters all are /have been on B12 injections as we all are deficient when diagnosed, not anaemic, all are negative for IF and P Cell antibodies, so no known reason why, just it is and that it's currently unknown why. Could be genetic, some bowel issues etc. But one thing is for sure you do not become B12 def easy (your body has stores for years, it is normally very careful with B12, takes it up daily, but also recycles what is already there etc). Something is not functioning right, unless you are a vegan, it is very difficult to become B12 def, so once you are you may well need treatment for life, what ever the reason for the initial deficiency.


-I got tested for PA 2 hours after my first b12 injection, is it likely to disrupt the test? They are doing an IF test and the dr and specialist nurse seemed to say that it should be okay...

There should be something like 6 days in between B12 jab and IF test I believe. .

Perhaps read this it will help you understand a lot more about B12 def and PA, and IF negative PA, treatment is still for life, see:


I hope this helps,

Kind regards,


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Thanks Marre, it helps knowing that someone else is going through this too!


I have no idea why I became B12 deficient. There are possibilities in family history but there are also other conditions present that may mean that it has been there but not picked up or spotted because symptoms have been put down to something else.

Whatever the cause the treatment will be the same so I'd go with Marre on just accepting that is the way things are for you.

I suspect my problem has built up over decades - I can certainly go back twenty years with a lot of the things that I've found have improved since I started to get my B12 levels right - some things go back even longer than that.

Engels is also correct that there aren't any clear cut tests that can be done that will decisively show whether a) is the cause or b) or .... so if you can try not to drive yourself mad worrying.

No information from GP is pretty normal - there are some good books out there - Pernicious Anaemia: the Forgotten Disease? and Could it be B12 just to name a couple and those are probably the best by way of trying to figure out what is going on.

I was told I was B12 deficient in a teaching hospital on rounds with a load of students and thinking back to the information I got back from the consultant and the responses from the students when he asked them about it I'm not sure any of them really had much of a clue what it was about. To be fair he was a bone specialist (I'd broken my ankle and had to have it pinned) but still there are some relationships with osteoarthritis and osteoporosis that may be should have come up ... in stead the only thing I really remember is the regularity of my bowel movements. Took me ages to really figure out what it was all about and how it was affecting me and my GP - a very caring individual - hasn't really demonstrated any clue as to what B12 deficiency actually means ... and I guess part of that may be the fact that B12 plays such a fundamental role in so much of the bodies working that the deficiency manifests itself in 100s of different ways ... and all of them easily mistaken for something else ... and nothing to say look at the whole picture and may be there is a common cause.

To be honest, since I found out I was B12 deficient I have yet to come across anyone who says that the normal regime suits them perfectly. Some people get close to the 2-3 months between maintenance shots but nobody I've come across says that they have to rely upon the diary to remind them when a shot is needed and complete strangers have described friends who spend weeks like zombies.

Its a complex vitamin, with a complex absorption mechanism, a lot of uses and a lot that go wrong. We are all individuals and we all respond differently.

And Engels is also very right about the use of the word borderline in relation to low. The low point of the range is probably set far too low and that undoubtedly contributes to the number of people who develop quite serious sets of problems before the cause is picked up and treatment started ... and in some cases that is too late to give the body a chance to actually repair all of the damage that has been done.

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PS - meant to say: I've not had anything show up in terms of abnormal sized red blood cells, and nobody has mentioned white blood cell oddities or platelets in looking at test results - so yes, perfectly possible to have a B12 deficiency without having actual anaemia.

Having said that though - since getting my B12 levels right my blood clots more quickly if I get a cut and I heal a lot quicker ... used to be a right little bleeder :)


Thanks for the reply Gambit62 :) Its good to know that its not just me going through this


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