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Pernicious Anaemia Society
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B12 levels, what is considered low?

Can someone please tell me what the levels of B12 blood tests should be to be considered low and required B12 shots? I am going to go and see my doctor and want to discuss past blood tests which I was diagnosed with Pernicious Anaemia and the most recent ones, which they claim that I now do not have it.

If anyone could give me some information on what is considered high, normal and low, I would greatly appreciate it?

14 Replies

Sorry I don’t have the measurements handy to be precise, but think the measurements are standard.

I felt wiped out at 300, though it’s within NHS normal. Some countries medicate below 500. I feel better with high dose sublinguals, & a level of 800.

If you have PA, it’s a lifelong issue, so medication is necessary forever. 💊💉🤕


I was told when diagnosed that I would need injections for life. I moved house and things were fine at my new practice, my injections continued but then there was a change in doctors and wanted meds reviewed. Suddenly I did not have pernicious anaemia anymore?!

Thanks for you information and support, I will be seeing my doctor again and will be challenging on this.

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Print the NICE PA guidelines, & wave it under the doctor's nose!

Good luck!


Thank you, I'm reading this now!

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So, is there any way of knowing that you just have low levels due to say, diet or whether it's PA?


My diet's very high, plus I take a B complex, but my results were low. They rose, & my symptoms reduced after I started a high dose sublingual. I swapped brand & errantly bough 500 rather than 5000mcg of methylcobalamin, & my symptoms returned until I increased the dose.

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You can't be cured of PA - its an auto-immune condition that attacks and destroys the mechanism that allows you to absorb B12 leading to a B12 absorption problem.

Serum B12 isn't a gold standard test and can't really be used as a single measure to manage B12 levels. It is measuring the amount in your blood - so it can be useful for diagnosing an absorption problem (eg showing levels dropping over time) but it doesn't tell you about what is going on with B12 where it really counts - in your cells.

If you have had treatment for B12 deficiency with shots - serum B12 isn't really a test that can be used to manage B12 levels - and the only real way of going after loading shots is to treat on the basis of symptoms. On average people who are being treated for B12 deficiency with shots report needing B12 levels to be around 1000pmol/L to feel okay - ie well over the top of the normal range - there are some that are way above that (mine are permanently off the top of the scale) and there are others who are perfectly fine in the normal range.

Not sure where you are based but in the UK the current recommendations are not to retest serum B12 unless there is reason to believe that treatment hasn't been complied with (really only applicable to oral treatment, eg to correct a dietary deficiency.


I live in Glasgow, I have recently turned 43years old.

When I was diagnosed I was told that my blood had enlarged red cells which were unusual in shape. I was also told that I had an absorption issues, whereby, I was not producing Instinct Factor which was needed to attach to B12 in my stomach to absorb it.

I really do not know much about blood tests or level but I will need to get copies of my tests to examine them and do a bit of research into what it all means.

When I was told I was Pernicious Anaemic, I accepted that I would need B12 injections for life, and they game me my life back...I felt normal again. I took for granted that I would get my injection and all would be ok. Now I will need to understand what all the results mean and thats had when focusing is just so difficult.

Thank you for you information and support, it is giving me the confidence to challenge my doctor about their decision to stop my injections.


GPs can be very confused and think that PA is all about anaemia so if you no longer have anaemia you are cured.

Injections manage the underlying cause by by-passing absorption in the gut. Someone without an absorption problem will be able to rebuild and access stores in the liver, but the release of these stores depends on the same process you use for extracting B12 from food - basically it is like having a huge reservoir but the connecting pipe is so leaky that none actually gets into the house. You are reliant on the amounts in your blood



If you 've been diagnosed with PA, treatment is for life. I'd suggest contacting PAS soon.

There can be potentially severe consequences of stopping B12 injections. There may be further deterioration including spinal problems.

PAS news item on Neuro Consequences of PA


Blog post that mentions SACD, sub acute combined degeneration of the spinal cord.


PAS (Pernicious Anaemia Society) can offer support and info about PA.

Costs £20 for a year's membership. PAS can sometimes intervene with GPs by writing letters on behalf of members and at very least can pass on lots of useful info to members.


PAS tel no +44 (0)1656 769717 answerphone

PAS has published a leaflet "Treatment is for Life" which some forum members have passed to their GPs. See "Articles/leaflets" in Resources section.


There are stories on Martyn Hooper's blog about people whose injections have been stopped and how PAS has helped. Just put "Injections stopped" in search box on blog website.


B12 Deficiency Info blog has post from Aug 31st 2017 about help if injections have been stopped.


Link about writing letters to GPs about B12 deficiency


CAB NHS Complaints


HDA patient care trust


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

Access to medical records (Scotland)


UK B12 documents.

I suggest reading all of these.

BSH Cobalamin and Folate Guidelines


Flowchart from BSH Cobalamin and Folate Guidelines


BMJ B12 article






There is a useful summary of mainly UK B12 documents in third pinned post on this forum.

If you are being denied treatment you are entitled to, then local MP may be interested.


B12 Books I found useful

"What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper. Martyn Hooper is the chair of PAS. Book is up to date with UK guidelines, I gave a copy to my GP.

"Living With Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Has several case studies

" Could It Be B12?: An Epidemic of Misdiagnoses " by Sally Pacholok and JJ. Stuart (USA authors) Has lots of case studies.

I am not medically trained.


Hi samyoung74 as others have said Pernicious Anaemia is for life not just for Christmas.

It is also important that your Folate level is monitored as this is essential to process the B12.

There is a complex interaction between folic acid, vitamin B12 and iron. A deficiency of one may be "masked" by excess of another so the three must always be in balance.

Symptoms of a folate deficiency can include:

symptoms related to anaemia

reduced sense of taste


numbness and tingling in the feet and hands

muscle weakness


Folic acid works closely with vitamin B12 in making red blood cells and helps iron function properly in the body.

Do you know if the "hard copy" of your notes were sent to your new practice?

In January 2014 I was given a print-out of my "Medical History" with the practice I have been a patient with since 1966 (52 years) and on it I noticed that I "had" P.A. on 27th March 1997 whereas in reality I received the diagnosis 25 years earlier.

The day in May 1972 that I went back to Dr Wool for the results of a "Schilling's Test" is etched indelibly into my memory.

It was on the Wednesday afternoon of 10th May that I duly presented myself at the surgery and Dr Wool greeted me with the words “Do you want the good news – or the bad news?” I said that perhaps she ought to give me the “bad news” first. She replied “The bad news is, that you’re going to die – and you’re going to die within the next two years”.

Naturally I was somewhat rather keen to know what the “good news” was.

So I asked Dr Wool what the “good news” was.

She said, with a mischievous twinkle in her eyes, “The good news is you’re not going to die within two years if you have regular injections (of vitamin B12) from now, for the rest of your life."

To the relief of both of us (as I think Dr Wool was getting a bit frustrated with my long, ongoing “condition” too) the Schillings Test had showed that I was suffering from Pernicious Anaemia. This “disease”, if untreated (until only a few tens of years before) usually led to an early death and the only known remedy then was a diet of raw liver three times a day. I’m not sure whether that was before, during, or after meals…

If you have no success persuading your new doctor it may pay you to join the Pernicious Anaemia Society click on the link below and scroll down


I am not a medically trained person but I'm still "clivealive" and over 75

I wish you well


PA is for life not just for Christmas cracked me up!

Good to have a little levity now and then on the days we can.


Hi everyone, thank you for your support it game me the confidence and information to challenge my doctor.

I got an 'on the day appointment' where you call in the morning and get allocated and appointment with what ever doctor is available. I was ready to be forceful, if necessary, in requesting that they reassess me. However, I seen a doctor who was not the one who took me off my injection and tried to say that I may have ME. She was great, I told her of my previous diagnosis and told her that Pernicious Anaemia was meant a life long illness, to which she quickly agreed. She spent time listening to how I got my diagnosis and searched for my haematology report but it was not on their system. She explained that they had their computer systems updated a couple of years ago and given that my diagnosis was over 10yrs ago, it my not have been added to their new system.

The doctor is going to get my file out and she said she will be happy to reinstate my B12 injections when she finds the diagnosis in my file. She has also ordered a load of blood tests to check all factors out to get me back on track, there include B12, Via D, Thyroid, Instinct factor antibodies. She has also arranging and ECG.

She did say that I should have had other blood checks done when I kept returning after having had my injection stopped and complaining of extreme tiredness, confusion and being forgetful. She will record on my file that I have PA when she finds the paperwork in my file and will ensure my injection are reinstated.

I feel a mixture of relief and anger. I am glad that I was taken seriously and listened to, with resolution on the horizon, but a tad angry that the other doctor could have had the same approach. I have not had an injection since July 2016. I quickly read in one of your posts that not having my sots could result in damage to the nerves in the spine. I was at the doctor about 4 weeks about about and pains that I was getting, which were isolated in deep in my spine. I was worried that I may have been developed issues with my discs but they thought is was more likely muscular. I knew it wasn't as i could feel it in my spine.

I will keep you informed of how my case progresses and I will be joining the PAS so that I can access all information I need to understand my condition better.




Glad to hear that you had a positive outcome to your appt. I note your GP has asked for Intrinsic Factor Antibody test.

Please be aware that if this IFA test comes back with a negative or normal range result, GP may say you do not have PA.

Some UK GPs may not be aware that it is possible to have Antibody Negative PA. See flowchart below.


It seems such a shame that your PA diagnosis is not on their computer system. Fingers crossed for you that there is evidence of PA diagnosis in your medical records.

I think it's probably worth you getting a complete set of your medical records once everything is sorted out to keep as evidence in case of future problems.

Might also be worth writing a letter to GP to back up what you said in appt. Letters to Gps should get filed with medical records so there will be evidence in your medical records that you raised the issue of a previous PA diagnosis.

I'm wracking my brains as to where else there might be evidence of your PA diagnosis in case it is not in your file.

1) Your dentist may have a record of diagnosis.

2) If you've been in hospital, PA diagnosis may be recorded on hospital records.

3) Any other health professionals you've had contact with.

4) Sometimes there may be clues in other blood tests. Do you have recent results for folate, ferritin (and other iron tests), full blood count as well as B12?



"and tried to say that I may have ME"

Not uncommon on this forum for people to have a ME/CFS diagnosis before B12 deficiency/PA found.




I am not medically trained.


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