Pernicious Anaemia Society

PA test after loading doses...Help?

Hi all,

I had an appointment with my GP yesterday as a follow up after my loading doses. (A little background, I had a B12 blood test done and was told my results were normal but when I asked for a copy these were just above the threshold for deficient so the GP agreed to give me the loading doses and see how I felt) I discussed with my doctor yesterday that I had felt some improvement although nothing drastic but definitely a noticeable improvement.

She advised that she was willing to prescribe B12 injections 3 monthly for 1 year and then review after this with blood tests. I voiced my concerns that after having the injections my B12 would be high so may not show up on a blood test straight away. She said that B12 deficiency is either caused by dietry or PA and as I was not aneminc it wouldn't be PA, I pointed out that you do not have to be anemic to have PA. I asked for the IF test to see if I had PA but she said she is not sure if the lab would do this as I was not anemic but would contact me.

So I am just wondering if because I have had the loading doses (4weeks ago was my last) if this will affect the IF test if she agrees to give me this?

She advised that as it is unlikely I have PA and each B12 injection is enough for 1 years supply that after having 4 more injections I should not be deficient but I am worried that I will slowly start to decline again.

Is there any logic in what she is saying and can anyone give me any pointers of what to do next for the next time I speak to her.


9 Replies

I notice from your first post Rachel that you have neurological problems and low B12, so your GP should be following and treating until no further improvement as per the BNF guidelines:

"The BNF advises that patients presenting with neurological symptoms should receive 1000 ug i.m. on alternate days until there is no further improvement".

Very few GPs understand the symptoms of PA/ B12 and are only looking for anaemia and large red blood cells, which is the last stage, may never appear, or be masked by high folate.

Here are more links in case you haven't already seen them and want to write or show your GP:

Cmim/BMJ document. " Summary:

* Vitamin B12 deficiency is a common but serious condition

* Clinical presentation may not be obvious thus leading to complex issues around diagnosis and treatment.

* There is no ideal test to define deficiency and therefore the clinical condition of the patient is of utmost importance."

* There is evidence that new techniques, such as measurement of holotranscobalamin and methylmalonic acid levels seem useful in more accurately defining deficiency.

* If clinical features suggest deficiency, then it is important to treat patients to avoid neurological impairment even if there may be discordance between test results and clinical features.

*It is important to recognise that clinical features of deficiency can manifest without anaemia and also without low serum vitamin B12 levels. In these cases, treatment should still be given without delay."

The above BMJ research document is supported by many research papers and is peer reviewed. It also states that, once b12 treatment is started, the test results don't mean anything and blood levels are not reflective of how effective the treatment is - it is the clinical condition of the patient that matters:

"Cobalamin and holotranscobalamin levels are not helpful because they increase with vitamin B12 influx regardless of the effectiveness of treatment,24 and retesting is not usually required."

" Starting straight away with treatment is essential, as is the continuing treatment in order to give the body enough B12 to fully recover. Therefore it is essential that patients are no longer exposed to the real danger of irreversible symptoms because of the imaginary fear of overdosing."

"After a year: The need for quick and correct treatment is emphasised further by the fact that after a year of treatment only 4 % of patients are fully recovered. Fortunately half of the patients have experienced a lot of improvement in their symptoms after a year of treatment but there are still a lot of patients with remaining symptoms, who could possibly have recovered if their treatment was started promptly and adequately."

I hope all goes well Rachael.


Well said, Polaris!

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She is clearly not particularly versed on the subject of B12 deficiency. Diet and PA are not the only reasons a person can become deficient. Gastric surgery, certain medications, or parasites can also deplete or hinder the absorption of B12. It's clear that she also doesn't understand that anemia is an after effect of B12 deficiency and not the first sign of a problem.

An intrinsic factor antibody test should, in theory, not be affected by injections of B12. But that test is far from reliable. It has a high accuracy rate if the test comes out positive but a rather low accuracy rate if it comes out negative (meaning that a positive result almost certainly means you have PA, but a negative result doesn't rule out having PA). Also, an intrinsic factor antibody test alone doesn't check for any of the other non-diet related causes. A parietal cell antibody test used to also be performed at the same time, because anything that is damaging the cells that line the stomach will keep you from absorbing B12 (as well as other nutrients). A serum B12 reading includes inactive forms of B12. If you're on injections, you may have quite a bit of B12 in your blood that your body may never be able to activate. That can lead to falsely high numbers.

Your options aren't great. You could either attempt to find a more knowledgeable doctor, or try to educate the one you have.


OMG another gp ...... what on earth can we do. I think POLARIS has answered all of Rachels questions - but I can only feel here we go again. another fight.


Oh and this bit "She said that B12 deficiency is either caused by dietry or PA and as I was not aneminc it wouldn't be PA" is also goofy, because B12 deficiency *for any reason* can eventually lead to macrocytic anemia. It is not true that only people with PA become anemic from B12 deficiency.

If you're willing to shell out the money, you could forward her a copy of 'Could it be B12?' and ask her to become more familiar with the subject in order to work with you to achieve your optimal health. (


If you want a collection of expert publications to back up your (completely correct) thoughts on testing and PA without anaemia download this -


It's true you do NOT have to be anaemic to have P.A. Your doctor should know this if she has any knowledge of P.A. Also , I had sky-high readings of B12 when I had the anti-bodies to the Intrunsic factor test(I was covered in B12 skin-patches and has been swallowing B12 sub-lingual lozenges all of which didn't help) I nevertheless tested positive for the antibodies, proving P.A. But you know (and she should know) that you can have P.A. without testing positive. It's all in the literature. Yes one B12 injection would probably be enough to last for a year if you didn't have the absorption problems , which you obviously have . You need to down load and print out fbirder's useful list of documents to take along to your doctor. . Best wishes


Yes, where do you start with a GP who has so many misconceptions and such a poor knowledge of the metabolism of b12.

b12 is absorbed in the ileum. There are a number of things that aren't PA and aren't lack of B12 in your diet that can cause a deficiency - including gastric surgery and drug interactions to name but 2.

B12 is stored in the liver and released into the ileum. This can be really efficient if you don't have an absorption problem - but if you do have an absorption problem this is a leaky bucket and you will become deficient.

Actually a shot amounts to about 3 years supply - however most of the B12 is filtered out and pee-ed away in urine in the first 48 hours. The rate of removal is larger the more B12 there is in your blood so it gets less over time. It also varies from person to person. 2 months is the average time a normal person takes to remove most of the b12.

Anaemia is a symptom of a B12 deficiency but is not necessarily one of the first to appear. I've had problems with depression and anxiety for 40+ years but never shown up with macrocytosis and a degree of neurological problems for 30+ years.

The symptoms of B12 deficiency are the symptoms of PA so quite possible that anaemia isn't going to be amongst the first symptoms to appear. The name PA is an historical anomaly as it was first classified over 200 years ago as a form of anaemia that lead to neurological problems and death. No way of knowing how many people were having neurological problems first as it wasn't observed that way.

The tests for PA are notoriously unreliable - probably about 50% so a negative result doesn't mean you don't have PA - just that the test result hasn't picked up PA. They can be affected by supplementation.

B12 deficiency isn't about the levels of B12 in your blood - it is about whether the cells in your body have and are able to process B12 - low levels in blood will obviously mean that the cells aren't getting much B12 but high levels don't necessarily mean that B12 is available at the cell level - there are a number of things that can go wrong leading to a 'functional' B12 deficiency.

hope that the materials fbirder has put together help - particularly having the references to scientific papers and guidance.

Unfortunately, your GP is far from being unusual


I am always so impressed with how knowledgeable you all are, Gambit 62, Polaris, Galixie, fbirder & wedgewood. Well done, everyone and thanks for explaining some very complicated info to me and others who read these posts! :-)

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