Will intrinsic antibodies show up eve... - Pernicious Anaemi...

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Will intrinsic antibodies show up even if b12 normal due to taking b12 tablets?


Hi all,

I just wanted to get some advice if possible. I have hashimotos for the last ten years but never felt right despite my thyroxine apparently correcting this. I've now discovered I have 22 symptoms on the pernicious anaemia symptom checker and yet whenever I go to my gp I get told it's down to my thyroid or I'm depressed/stressed. My dad and my gran both have pernicious anaemia and have 3 monthly injections yet my b13 hasn't been checked for nearly 2 years. When it was checked it came back as 177 once and 149 once. The reference level at my lab is 130-800 but yet where my family are they treat below 190. I was just interested to know what other people's levels were who are getting treated? Also my doctors have now agreed to check it again and also for intrinsic factor antibodies and parietal cells. However I've been taking b12 supplements the last month and I'm not sure how long to leave it before having the tests? I've been off the supplements for a week now. Also will the intrinsic factor antibodies show even if the b12 levels are now normal?

Would really appreciate any advice!


12 Replies

Hi Cathyjw, with a family history of PA and b12 levels as low as yours I would be very surprised if you don't have PA. What form of b12 were you taking and what was the dosage?

B12 can interfere with the assay for intrinsic factor antibodies so it is good that you have been off them for the week. When is your test? Having said that, anti-IF tests can give false negatives so it's not the best test for PA. (More on that in the thread link below).

I feel that you should be treated based on your family history, low b12 level and your symptoms. I know how difficult it is to get the treatment that is needed. At this point, I would strongly advise you to get copies of all of your medical records and tests and consider finding a GP who will listen to you. It is good that you have your symptoms list, keeping a record of your symptoms throughout treatment is going to be key in getting better.

There is a previous thread on this forum which addresses the same question that you have. There is so much helpful info in it from the Admins and Forum Support members.


The question you have is answered here, third paragraph:


"Taking supplements that contain B12 will affect any tests ordered by your doctor to assess your B12 status. You should not take any supplement with B12 before having your B12 assessed (including MMA/homocysteine/Active B12). For testing intrinsic factor antibodies: keep one week between an injection and the test. "


Thank you so much for the reply! I was taking vitamin b complex from ASDA. It was 1 tablet a day and it contained the RDA for b12 and folate in it. I think for b12 it was 2.5 something which was 100% rda. I work at the hospital so I can get my tests done any day but next doctors appt isn't until 9th Aug so I was trying to wait as long as possible in the hope some of it might leave my system again. In a way I'm praying the antibodies show up as my doctor even said to me "well you can have that test and if it's negative we can rule PA out". :( so difficult to get them to understand! I have spoken to the society and joined as a member so I will contact them again if I have no success.


"The reference level at my lab is 130-800 but yet where my family are they treat below 190. "

Are you in UK?

I'm asking as patterns of B12 treatment vary from country to country.

In UK, the emphasis in UK B12 guidelines is on treating people who are symptomatic whatever the B12 level.

Are you symptomatic for B12 deficiency?




Unfortunately this emphasis in official UK documents on treating symptomatic patients is sometimes not followed by some doctors......

If you're in UK, I'd suggest reading

1) "BSH Cobalamin and Folate Guidelines".

It's a UK b12 document that was published in 2014 and it outlines diagnosis and treatment of PA and B12 deficiency.


Flowchart from BSH Cobalamin and Folate guidelines


Flowchart above makes it clear that in UK, people who are symptomatic for B12 deficiency should

a) Have an IFA test

b) Start initial b12 treatment before results of IFA test come back

This applies whether or not B12 is low or within normal range.

Flowchart also outlines when PA and Antibody Negative PA can be diagnosed. IFA test is not always reliable and it is still possible to have PA even if IFA result is negative.

2) BMJ B12 article


Emphasises need to treat people symptomatic for B12 deficiency even if no obvious deficiency in B12 blood test in order to prevent neurological damage.

3) Link about writing letters to GP about B12 deficiency.

Point 5 is about being symptomatic with normal range B12 result.

There is a link on page to UK NEQAS B12 Alert which emphasises importance of treating people with normal range B12 who are symptomatic for B12 deficiency.


4) Lots of B12 info in pinned posts on forum. I found fbirder 's summary of B12 documents helpful to read. Link to summary in third pinned post.

5) B12 books

"What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency2 by Martyn Hooper. Martyn Hooper is the chair of PAS (Pernicious Anaemia Society).

"Living with Pernicious Anaemia and Vitamin b12 Deficiency" by Martyn Hooper. this book has several case studies. I coudl recognise aspects of my experience when I read them.

"Could it Be b12; an Epidemic of Misdiagnoses" By Sally Pacholok and JJ. Stuart (USA authors).

Very comprehensive book about B12 deficiency.

6) PAS (Pernicious Anaemia Society)

Some people on forum join the PAS. They are helpful, sympathetic but busy and may not have resources to help non members. They can sometimes intervene on behalf of members by writing letters.

PAS members can access details of local PAS support groups and PAS documents/leaflets.


Local groups can be useful sources of info eg helpful GPs/consultants.

PAS contact details


PAS tel no +44 (0)1656 769 717 answerphone so messages can left

Other B12 websites


There is also b12d.org

7) B12 blogs

Martyn Hooper's blog has stories about people struggling to get a diagnosis.


There is also an interesting blog on "B12 deficiency Info" website which includes a post about how reference ranges for B12 vary across UK.

Unhappy with treatment (UK info)

Letters to GP


CAB Citizens Advice Bureau


HDA patient care trust

UK charity that offers free second opinions on medical diagnoses and treatment.


What to do next if B12 deficiency is suspected?


"told it's down to my thyroid or I'm depressed/stressed. My dad and my gran both have pernicious anaemia"

Risk Factors for PA and B12 Deficiency




Some on forum have discussed the potential consequences of no treatment/undertreatment of B12 deficiency with their GPs.

There is an article about SACDSC (sub acute combined degeneration of the spinal cord) in PAS library section on website.


Story below on Martyn Hooper's blog mentions SACDSC.


Access to Medical Records




It can be very illuminating to see what has been written in medical records.

I personally get copies of all my blood test results. I learnt to do this after being told everything was normal and then finding abnormal and borderline results on the copies.

I am not medically trained just someone who has struggled to get a diagnosis.

Cathyjw in reply to Sleepybunny

Hi sleepy bunny,

Thank you so much for all the information I really appreciate it . I am in the uk but my doctor thinks that if my intrinsic antibodies come back as negative it means they can rule out pernicious anaemia. I also spoke to another gp who told me if my b12 levels were 149 it couldn't be that as it's normal range :( I am symptomatic for b12 deficiency and have been for at least 2 years if not longer. I also used to think it was just all a result of having an under active thyroid with many endocrinologists telling me it was normal to not feel normal anymore! It was only when severe brain fog, confusion etc kicked in that I thought it must be something else. My doctor thought I was mad - made me do a memory test for dementia and sent me to a neurologist who basically said it was psychological. . Until now I had given up! I've joined PAS And started reading one of Martyn's books and I can't believe how much it all fits me and how appalling the situation is in the UK. Will definitely look at all the other links.

Sleepybunny in reply to Cathyjw

"my doctor thinks that if my intrinsic antibodies come back as negative it means they can rule out pernicious anaemia. "

"spoke to another gp who told me if my b12 levels were 149 it couldn't be that as it's normal range"

The flowchart from BSH Cobalamin and Folate Guidelines makes it clear that in UK, Antibody Negative Pernicious Anaemia can be diagnosed.

There is a section on PAS website for health professionals that your GP may find useful and leaflets/info in PAS library section that you could print off for GP.


I believe Martyn Hooper tested negative more than once before finally testing positive on IFA test.

I gave my GP a copy of BSH flowchart and rest of BSH Cobalamin and Folate Guidelines because I did not think they knew about this document.

I think Antibody Negative PA is mentioned in Martyn Hooper's book "What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency"

I gave a copy of this book to my GPs and I also gave them a copy of PAS Symptoms checklist with all my symptoms ticked plus I added any not on list. I made sure I included every neurological symptom I had.

There is more than one UK b12 document/article that I gave a link to in above post that emphasises the importance of treating symptomatic patients even if normal range B12, in order to prevent neuro damage.

I have several times in past written letters to GPs with my queries about treatment.

Letters could contain info about symptoms, test results, extracts from UK b12 documents, consequences of undertreatment, family history of PA.

I was told once that letters to GPs are filed with a person's medical notes so are a permanent record of an issue being raised.

UK b12 treatment

In UK, those who are symptomatic for B12 deficiency with neurological symptoms eg tinnitus, tingling, pins and needles, memory problems, balance issues plus other neuro symptoms are supposed to get more intensive treatment.

info on Uk b12 tretament is in

1) BNF British National Formulary Chapter 9 Section 1.2



BNF is a slim book all Uk Gps have access to, probably a copy sitting on desk or bookshelf. Possible to get own copy from good bookshop or popular internet retailer.

2) BSH Cobalamin and Folate Guidelines

Treatment info is about a quarter through document.

Reading the forum suggests to me that there are quite a few doctors in UK who are not aware that the treatment for those with B12 deficiency with neuro symptoms is more intensive than for those without neuro symptoms.

Route to diagnosis can be a long hard process. Sometimes I think it takes time to collect enough evidence. There are consultants and other health professionals who may be able to help.

Have you been referred to or seen

a haematologist?

a neurologist (if you have neuro symptoms)

gastroenterologist (for gastro symptoms)

podiatrist (for neuropathy in feet)

dentist (bleeding gums, mouth ulcers)

opthalmologist/optician (changes in eyesight)

audiologist (changes in hearing, tinnitus)

endocrinologist (glandular, hormonal symptoms)

rheumatologist (joint health)

I'm sure there are other "ologists" I haven't thought of. I saw several "ologists and very few had what I considered to be a good level of knowledge of b12 deficiency.

My dentist knew what to look out for in terms of b12 deficiency symptoms that affected the mouth/tongue and optician knew about potential effect of b12 deficiency on eye health.

Best person I saw was a neurologist who raised possibility of B12 deficiency with my GPs, Unfortunately GPs at time did not take this on board. I did see other neurologists though who I felt were not helpful.

You mention PA in family and thyroid problems. Having auto-immune conditions in family increases chances of developing one.

Have you ever been checked for Coeliac disease?


Are you in a position to go privately?

Don't forget that HDA pct can offer free second opinions on medical treatment and diagnosis....think they use a network of consultants around UK.


The threshold seems to vary within the UK too. My B12 was 133 and the threshold on my blood test was 180-700. So OP's 149 would have been well under. Seems bizarre they can have different thresholds depending on where you live.

The strange thing is that when I had PA and my serum level was 150, I was sent on my way by my GP , ( nothing wrong with me , my numb feet were ideopathic)so I supplemented with B12 sublinguals , patches all over my body , sprayed up my nose ,. I went to a private hospital for a diagnosis . My B12 was naturally off the scale , but the IF antibodies showed up in spite of that!So I had PA. So I really don't know why the advice is to stay off the supplementationof B12. May be mine was just freak . I don't know .

Cathyjw in reply to wedgewood

That's really interesting to know thank you. Did you need a referral for the private hospital? Did the self supplementation help you feel better?

wedgewood in reply to Cathyjw

No I didn't need a referral ( it was a Nuffield Hospital . I just telephoned and booked an appointment for 3/4 hour .) I had been supplementing like mad for at least 5 weeks with no effect at all . If those supplements had helped I probably wouldn't have bothered to consult the private GP . Injection is the only method that works with me. Strangely ,injections are a cheap form of supplementation at £1 a shot ,when everything is bought in bulk


IFA and PCA are tests for a specific cause of B12 deficiency, PA. For an IFA test you generally need t have refrained from supplementing for 7-10 days. Not sure about PCA.

IFA is notoriously prone to false negatives - 40-60% of time depending on the assay method - so a negative is a long way from ruling out PA.

I think you have to be off the suppliments so you dont have a false positive intrinsic factor test.

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