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What exactly is Functional B12 Deficiency?

I was told I had B12 deficiency(196) and had 6 loading injections then 1 every 3 months. By the 2nd of these 3-monthly injections, I did not feel any benefit and had got a lot worse in terms of symptoms. Blood tests 6 weeks after the 2nd injection, and told MMA level was raised (351) and that because plasma B12 was over 2000, confirmed "functional B12 deficiency"- although I thought over 2000 would be expected after injections started : it's confusing to me.

Since then have been reloading: the first 5 did nothing, so improvements, even minor ones, delayed. I have now had about 14 loading injections altogether (2 a week), feeling slightly better but some of the nurses are getting reluctant to give me any more before seeing GP again, although she said no need to see her again, and to go on to monthly injections when no further improvement. This is clearly very new to them. I'm seeing Dr on Thursday pm, for a certificate, but also I'm guessing to have a review of new programme- don't even know what to ask for/ rule out any more.

My cousin has very recently been told she is B12 deficient too. Don't know her details yet.

I've been trying to sort out what exactly is wrong with me for almost 2 years now. Hip bursitis, lower back pain, diarrhea, dizziness, cognitive difficulties, mood swings, need for sleep, need for solitude, fogs, sensory overload, muscle weakness in limbs,trouble fighting off infections and hair loss (at least that has stopped currently) all still there but improved. Still problematic getting all these recognised as related symptoms- especially by gastroenterologists, who have not done any tests because I don't have a stomach ache, and /or they believe I have IBS. Give me strength!

I've had lots of blood tests, ferritin and folic acid being treated as both within range but low. All else on FBCs etc seems very mid-range normal as far as I can see. No liver problems. Can anyone help?

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Functional B12 deficiency is B12 deficiency at the cell level although serum levels are high.

Basically something goes wrong with the mechanisms that transport the B12 from your blood and transfers it to the cells where it is needed. It is generally an autoimmune response triggered by high levels of B12 in your blood, as your body responds to the high levels in serum by shutting down the transportation. I don't know if it is linked to any other similar responses and I'm sure there must be some as it would make sense for the body to respond to high levels of substances that could cause damage by shutting them down.

B12 doesn't have any known toxicities so it is a response that doesn't make much sense and just leaves you without B12 at the cell level. In theory the response would stop if levels dropped below the point at which the response kicks in but this could take a very long time, leaving you very ill for a very long time.

I visualise it as being like a dam built to stop flooding but which has the undesired effect of actually causing a drought. The only way to get water on the other side is having it trickle over the top - which means keeping the levels of water very, very high so just enough trickles over the top.

The fact that your MMA was really high was the demonstration that your cells weren't getting enough B12. MMA is a waste product that builds up if your cells don't have enough B12.

Sometimes functional deficiency is used to cover cases where serum B12 is in the grey range but people are highly symptomatic but strictly speaking functional deficiency involves high levels of B12 that are above the normal range. The fact that some people are lower half of normal range but highly symptomatic is more to do with the fact that people vary significantly in the amounts of B12 they need to function properly.


Note: functional B12 deficiency can arise without artificial supplementation (B12 shots) in some conditions which stop B12 a person who is able to absorb B12 normally being cleared from the blood eg by the kidnesy, with the consequence that B12 levels in the blood get higher and higher. The patient will present with all the symptoms of a B12 deficiency but the B12 serum level is abnormally high.

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That's a fantastic explanation.... thanks Gambit62


Thanks, Gambit, this is really useful to me.

Theory about dropping to a point below response level sounds scarey to me since I was very ill already and had been for a year at least when diagnosed as deficient at 196 (range stated at 197 upward -so only just) but MMA not measured at this stage.

Not sure I can go there again.

Gambit, in your experience, is it possible to get the high levels needed recognised by and supplied on the NHS, or am I wasting very precious energy on this ? Do ALL people with "functional B12 deficiency" diagnosis end up self-injecting?

Can B12 be measured, for comparison, at cell level at all?

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a) personal experience - gave up on GP but then started from 40+ years of low expectations. however, there is this article from afew years back so it obviously is possible


although I supplement not all of that is by injection - use nasal sprays as the mainstay of my supplementation - and some adenosyl sub-linguals. I could probably get away without injections at all - though they are quite a convenient way of starting the day.

b) As far as I know there is no general way of measuring directly what is happening at the cell level. There are a couple of tests that look at build up of waste products that can indicate if there is a deficiency at the cellular level but I'm personally not entirely convinced that this always works whilst you are supplementing and I've never personally gone down that route. There is a test for TCII antibodies but I've only heard of it being done in relation to specific studies and no idea how much it would cost or where you would get it from. TCII antibodies have been identified with functional deficiency but I've no idea if they are the only thing that is linked to functional deficiency

Basically there doesn't seem to have been much research on functional deficiency or the incidence of functional deficiency in people receiving treatment for B12 - was a study in denmark in several decades ago but haven't been able to track down any paper directly coming out of the study - mentioned in this paper - reference 65


totally with you on not being able to go there again. Think it is a strategy for some people if the clear B12 quickly from their blood stream and would also depend on what the trigger point is. There have certainly been posts from people who find that 0.5mg doses of hydroxo work better for them than 1mg

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Luckily for me, I have had the benefit of your advice and a GP willing to listen and learn about functional B12 deficiency from people who have had to live with this condition. She is also not afraid to use her eyes- recognising that, within a month, there had been visible improvements. Have given her the notes from your advice and Foggyme's - she's bright and curious and has 2 patients with this problem. Your help is reaching so many more people than you know, and may one day restore your faith in (some) doctors.

Have a peachy weekend, Gambit62


Dear Gambit - I hope it's ok to bother you with a question regarding this topic?

I have PA (at least lots of parietal cell antibodies) but has managed to get rid of most of my symptoms by taking large doses of sublinguals. At some point this summer a few of my symptoms came crawling back. I was taking 15.000 mcg every 3 days (+ 5 mg folate on the same days, and a b complex every day). My lovely new GP took a blood test which showed b12 and folate over the

range. I started taking 20.000 mcg every other day, to make it 'trickle over the top' - which seems to help. Symptoms intensified and are now disappearing - hurrah! (One of them being urine incontinence 😣).

The big question is: What do I do from now on? Do I have to continue the 20.000 mcg every other day regime, or can I at some point cut down? Will the functional deficiency get worse if I continue? Do I have to continue the 5 mg folate or can I do with less?

Thank you for taking your time to read this!


Brigitte, to be honest I really don't know - it may be that it would be better to go for lower doses more often as what you are trying to do is keep the levels in balance. The rate at which you lose B12 gets greater when the levels in your blood are higher so just putting in very big doses every other day may mean that most of that is just being removed by your kidneys - and ends up going down the pan.

Quite possible that once recovery is over the amount that you need will also disappear but not sure how significant that is going to be as most of the loss is from excess being removed by the kidneys.

I found that adenosyl B12 helped me with urinary incontinence.


Thank you so much for answering 😊

Nice to know about the adenosylcobalamin!


it worked for me but that doesn't necessarily mean it will work for you but is worth giving a try.


Actually, I used to take it alongside methylcobalamin, maybe the incontinence came back because I took only methylcobalamin for a while, and is going away again now because I started taking some adenosylcobalamin again as well - just to use up what was left - I have read so much about pople only taking methylcobalamin that I thought I was foolish using both! Have ordered some more and will try with less b12, but both forms 😊 Thanks again!


Hi Cherylclaire.

What Gambit said πŸ˜€ (brilliant explanation) and...

How to deal with your GP appointment....

Based on Gambit's explanation looks like there are two possible options:

1. Either keep your B12 levels very high so that some trickles over the top of the dam (to follow Gambits analogy)

2. Stop B12 until your levels drop below the level where this response takes place (again, as Gambit points out, this could take a very long time).

As I see it (and this is only me thinking), there's no knowing how long option two will take and, more importantly, nobody can say for sure what (if any) damage is being done in the meantime (due to the potentially ongoing state of deficency at a cell level).

Think this is what they call being stuck between a rock and a hard place πŸ˜–.

Turner and Talbot (2009) wrote a paper on the subject of functional B12 deficiency, their conclusion being that patients with functional deficiency may respond to high doses of B12.

As for the nurses....well, they obviously haven't heard of the neurological regime for B12 deficiency. I should point them back in the direction of the GP who authorised your frequent injection. And better still, also point them to the PAS website - it has a section for medical professionals - they might be able to educate themselves πŸ˜€.

The good news is that you are feeling slightly better....so some B12 must be getting through to the the cells (albeit not quit enough yet).

Even in the absence of functional B12 deficency, recovery can take some time, especially when the deficiency has been present for some time prior to treatment.

So don't lose heart...at least now you now know what is happening to you and the slight improvement gives rise to the hope that this will continue.

Good luck and let us know how you get on πŸ‘

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Foggyme, what do you think?

Will NHS be likely to supply high doses of B12 indefinitely?

Would they be more likely to agree if some further proof supplied of deficiency at cell level....is that even something that can be tested for?

Anything else you could suggest in terms of testing that might improve chances of ongoing treatment?

I am a lot better but STILL feel like I had a dogbrain transplant.


The only way of testing this is to keep an eye on your MMA and homocysteine levels. There are no direct tests of B12 deficiency at cell level.


Hi Cherylclaire.

The first thing to say is that you already have proof that your have functional B12 deficiency (the high serum B12 together with the high MMA).

There are other tests that can be done but as far as I am aware, these are usually only done for research purposes (can't recall what they are and don't have time, right now, to look them up - TC11 antibodies, and other things, I think) but will do so if it becomes important to you).

How long will the NHS provide frequent (high) doses of B12 - theoretically, the neurological regime of every other day until no further improvement could be followed for many months - but many struggle to get this and there does come a point (for some) where no further improvement takes place.

So....how to deal with this...here's some thoughts that might help..but they're only my thoughts..

I think the key here is getting your symptoms under control - the right amount of B12 is going to be the right amount of B12 to get you as well as possible and keep you as well as possible. And it might take some time to work that out.

Getting treatment from your GP will, I think, rest on providing as much evidence as possible for the B12 regime you need to keep you well.

Some things that might help with getting treatment from your GP:

Keep a symptom log so that you can track and monitor your symptoms, in particular in relation to when you have your jabs (perhaps a spreadsheet where you record all your symptoms, on a daily basis (at least to start with), giving a severity score between 1 and 10 - noting down when you have your jabs. A pattern should emerge and you should then be able to start predicting how often you need B12 to keep your symptoms at bay. You will eventually be able to adjust the frequency of injections needed (perhaps longer between jabs) and will be able to tell what the right frequency is for you - and this may change over time. More importantly, your GP will have 'evidence' about the efficacy of your treatment (or not). Theoretically, it should be easier to get him to agree to an individual B12 regime that suits you, rather than a regime imposed by misunderstanding or guidelines that do not suit your individual needs. (I understand that this worked very well for fbirder.)

Start an 'evidence' file for your GP (more difficult to argue with evidence).

Get hold of hard copy evidence stating that you have a functional deficiency (this might be a copy of your blood results and / or a letter from a conultant saying that you have this).

Print off anything you can find on the PAS website about functional deficiency. Likewise from b12deficieny.info (not sure how much there is, but worth a look). Also try b12d.org.

Search the Internet for anything you can find about functional deficiency (bit only use sources that are underpinned by a medical research based approach - avoid woo woo sites).

If you PM me an email address, I'll send you a copy of the Turner and Talbot paper - hard research based evidence that high dose treatment is the way to go (at least when this research was done, and there hasn't been a lot published since - though new research may be in progress - a good question for the PAS conference, I think, and looking forward to new PAS science blog going live inDecember). Your GP will not be able to dismiss this.

Once you have out your reasearh file together, it might be a good idea to make a double appointment with your GP to go and discuss functional deficiency (you will probably have to educate him πŸ˜–) and ask if you can develop a care plan together (with agreed frequencies for B12 injections - and treatment review plans).

If you can get your GP on board early and put a plan in place think it'll reduce the stress on you and enable you to focus on recovery - rather than contentious and potentially difficulty GP consultations. Ask him to brief any surgery nurses - for the same reasons.

Also might be a good idea to take someone with you as a witness - a witness sometimes turns a GP into a more approachable and amenable creature.

The only other thing I can suggest - Guys and St Thomas hospital in London have a specialised interest in functional B12 deficiency - very well worth asking your GP to make enquiries and refer you there for treatment. This should not be a problem as you have a proven functional deficiency. Interestingly, they would be able to perform the additional tests I spoke about earlier (if they thought it necessary).

Anyway, these are just some thoughts that might (or might not πŸ˜€) help.

Be really interested to hear how you get on.

Take care πŸ‘


Foggyme, can't thank you enough, so here's the update and it's VERY good news...

Went to the Dr last night and firstly, she was delighted to tell me she could see how much I had improved in a month. She is going to send me to St. Thomas' neurology dept. next because of my cognitive, sensory and memory problems, told me this was not her area of expertise and that she had another patient who also has functional B12 deficiency with neurological symptoms, so seemed quite happy to accept my notes from all the advice given to me by you and Gambit. Quite a lot to take in but did highlight areas- she is going to look into who might be interested specialists at Guys & St Thos. Also said to carry on loading as it was clearly working, and that she would speak to the nurses about this! So on the strength of that, I booked one up for tonight! (Bet THIS one's going to kill!)

Two last things:

I will need surgery soon on torn rotator cuff- anything I need to know about specific anaesthetics & effects on B12?

"If you PM me an e-mail address" : I most certainly would if I knew what it meant and how to do it!


Wow Cherylclaire...this is just fantastic news πŸ˜€πŸ˜€πŸ˜€.

A doctors who listened, recognises functional deficiency, orders frequent B12, and refers you to the right specialist...my eyebrows are on the ceiling and my jaw is hitting the floor.

You must have worked really hard to make this happen...so very well done πŸ˜€.

Anaesthetic - nitrous oxide, a gas sometimes used in anaesthetics, deactivates all B12 in the body. There are other things that can be used so there is no need for you to have this. Tell,your anaesthetist you have B12 deficency and you do not want to be given any (some are aware that it's contraindicated, some are not). Also tell the nurse (in fact tell everybody involved) who does your pre-op check. I write it 'B12 Deficiency- Do Do Not Give nitrous Oxide' in block letters on the top of the consent form and also ask for a red allergy label to be attached to my wrist.

How to PM: There's an icon with your user name in the top toolbar on the left hand side. Click on this and a drop down menus will appear. Click the message tab and the messages page will load. Click the green 'compose' tab (top right of that page' and a new message 'thingy' (for want of a better word πŸ˜€) will appear. Type in the name of,the person you want to mail (in this case Foggyme) and click on the Foggyme tab - that name will be inserted in the message address bar. Type away and press send. Hey presto - message done.

Will send paper pronto.

Lots of people here ask questions about functional deficiency...but not a lot is known so...anything at all that your discover from the London end....would be great if you could post the information. And updates....'cause we'll all want to know how you're doing.

Oh this has really made my weekend...but I bet not as much as it's made yours πŸ˜„.

Well done, well done, well done πŸ˜€.

P.s. Think your GP deserves two gold stars (and that's a first).


Glad I caught you before leaving the library - I've got 13 minutes' use left so I'll make it quick. Trust my Dr and really like her. Yes, this has been a long, frustrating journey for us both but she never stopped trying, and I went along with (almost) everything she suggested even if only to eliminate it. That is why she will also accept that little is known and much can be learnt from those who have had to live it.

Too dog-brained right now to concentrate on instructions on how to PM but will, believe me. Of course I will let you know: none of this would even happen without you - and a Dr who is willing to stick by you, of course.

"Lovely job, tell yer mother" as my old carpentry apprentice-master used to say!


Yay to that πŸ˜€. PM whenever...no rush, will keep an eye out for incoming.

Dog-brained...know it well...hope you perk up soon πŸ˜€

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You all might as well be speaking Greek to me! I have been self injecting for seven weeks, ever other day. I take Vit D3K2, folic acid, b6, magnesium, b complex and alpha lipoic acid. I have less burning, but to be honest with you, I'm ready for a wheelchair, too! I've tried exercise but no results. I have weak extremities and sleep all day long. My toes feel funny (no pins and needles). I'm soooooo discouraged. I'm about to be self tested for the MFTHR genetic defect but I am sooooo discouraged! Would you send me a copy, too, of that Turner and Talbot paper? I am lucky to have a dr. Who listens to my research without dismissing me. I am 62.


Hi Blinkysmom. I'm so sorry that you're having so many problems and feeling so unwell.

And yes...talking B12 deficiency is sometimes like speaking an unintelligible 'other' language - it can be quite complex, especially when new to it and feeling so unwell...oh that brain fog nightmare.

Repairing the damage from B12 deficency can often take some time, particularly where neurological symptoms are concerned. Unfortunately, there are no hard and fast rules 'cause we're all different, have different symtpoms, and recover at different rates. So please don't despair...there was a post sometime ago from a forum member who had been self injecting every other day for a year - and neurological symptoms suddenly disappeared. And one from another member who was finding that they could walk in a straight line and feel their feet again. So, these things can take quite some time. Annoyingly.

It worth noting that neurological symptoms can have many causes, so if your neurological symptoms continue, it would be usual to be referred to a neurologist to rule out any potential underlying causes (if only for your peace of mind πŸ˜‰).

It's good that you have a supportive GP and are able to inject every other day - so keep on with that regime πŸ˜€.

Just a couple of throughts (but excuse me if you're already aware):

Has your GP checked your folate levels recently (I see you supplement with folic acid). Asking because too much folic acid can give some quite nasty side effects (very similar to those of B12 deficency) - and long term, can be quite dangerous. Not everybody with B12 deficency needs to take folic acid, so worth checking your levels to ensure they're not too high.

Also - I note that a B complex (which will contain vitamin B6) and a separate B6 supplement. Worth checking how much B6 you are getting altogether. (Many B complex tablets contain well over the recommended RDA (sometime 300%+).

Over-supplementation with B6 (pyridoxine) can cause neuro-toxicity and hence neurological symptoms/neurological damage. Many people do not need to take B6 and if your levels were normal range, even taking o lay the RDA may well be too much and cause problems.

Perhaps your GP would check,your B6 levels for you so you can decide if you need it...and how much you should take (I certainly wouldn't take it in a B complex and in an additional form as well).

Ferritin - often gets low when absorption problems are present - again, perhaps your GP could check this.

Same for Vitamin D.

Functional deficiency in one sentence - basically, it means that there is plenty of B12 in the blood (high serum B12 levels) but for various reasons, the B12 can not be transported from the blood and into the cells, and hence to the systems in the body where it is needed. This is not well researched (though research is ongoing) but what little there has been suggests that the best way to do with this is to keep serum B12 levels high - or very high. So, alternate day injections is good.

It's also worth noting that some people have to inject every day to get and keep well (even in the absence of proven functional deficiency).

MMA blood test - your GP may like to consider this. If you have a functional B12 deficency, the MMA will be raised (even in the presence of a high serum B12). (MMA is mediate and processed by B12 from the cells so if there is I sufficent B12 in the cells - a functional deficency - the the MMA cannot be processed - and the level rises.

About MFTHR - this is more to do with processing folate rather than B12 (though folic acid is obviously needed to process B12 as they work together). Some people (but very few) with two specific gene variations benefit from taking methyfolate instead of folic acid.

However, most people with an MHFTR variant do well with folic acid and don't need to take methyfolate (which can give quite nasty side effects - and is contraindicated in some gene variations). There's lots of hype on the Internet about MFTHR - usually put there by folks trying to sell methyl folate.

Is it worth getting tested - don't know. It's a very expensive test so be worth looking at some obvious things first: folate, ferritin and vitamin D levels - and potential over-supplementation with B6. And keepin mind that recovery from deficiency can take sometime, especially if you've been B12 deficency for a while.

Anyway Blinkysmom...here's links to some papers that you might find interesting - and can perhaps share with your GP too (can't tell you how good it is to hear about a GP who listens πŸ˜€πŸ˜€):

academic.oup.com/qjmed/arti... (High Serum B12 Levels: Functional B12 Deficiency)

cmim.org/pdf2014/funcion.ph... (BMJ: Vitamin B12 Deficiency: Treatment Review)

bloodjournal.org/content/bl... (Haematologist B12 Treatment Review March 2017 – Includes Advice No Reason to Advise Against Self-Injection/More Frequent B12 Injections)

PM on the way about the Talbot/Turner paper.

Keep up the every other day injections - and don't despair if it takes some time to notice real improvement.

Good luck and let us know how you get on.

Take care πŸ‘

P.s. Always a good idea to start a new post rather than reply to a very old one - nobody in the forum will see the reply you've left here (only me - 'cause you replied to me) and you'll always get more help/more answers for a new post that the whole forum sees πŸ˜‰πŸ˜‰πŸ˜€πŸ˜€πŸ˜€πŸ˜€


Hi Foggyme - couldn't get anything from your first link

( silverchair one )- hope Blinkysmom had better luck. All others were fine.

Also useful link from fbirder below- especially if anyone has a GP that will only look at NHS publications !

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Hi Cherylclaire. Try this...different site, same paper (seems the paper is no longer available on the site I gave above).

academic.oup.com/qjmed/arti... (High Serum B12 Levels: Functional B12 Deficiency)

Will insert new link for Blinkysmom πŸ˜€πŸ˜€.

Thanks for letting me know πŸ‘

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Thanks Foggyme , thought I'd read everything but this one I've never seen before.

For those printing off directly to read later, I'm thinking of Blinkysmom in particular, a word of caution: over 100 pages there........ you just need the first 14 or so.

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Blinkysmom - Another warning: having now read this, there is a lot of mention of cancer here. Also some discussion surrounding injecting B12 being deemed unnecessary- even for those with a diagnosis of PA.

Think the mention of cancer discovery in people with high MMA levels is because it could become a very useful tool in early diagnosis of hard-to-detect cancers in soft organs etc. Fair do's. Best to eliminate this first. Certainly, my GP's first thought was that I could have cancer.

Not so happy about dismissing need for Pernicious Anaemia sufferers etc. to retain their hard-won "injections for life" status.... sounds a little like personal opinion and cost-cutting. GPs might use this as an argument to stop supply, and PA sufferers would have to then prove all over again that they are deteriorating. Dangerous game. My opinion. I think Stichting B12 Tekort report (on sublingual vs injecting) would agree with me there.

I have read previously that mildly raised MMA is most likely to suggest functional B12 deficiency which leads me to suppose that extremely high levels are more suggestive of cancer, but that is just supposition. My MMA level is currently 393 nmol/L (range 0 - 280nmol/L) and I have had it checked now 4 times, all on NHS, and always considered mildly raised (not sure where the line is drawn here).

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100 pages πŸ€”πŸ˜±...that's really odd Cherylclaire. When I open the link, can only access and see the 14 page paper.

Haven't tried sending it to print so thanks for the warning...100 pages would be a bit of a shock (though I'd be curious to know what the other pages actually contained).



Have you had a chance to read it yet, Foggyme ? I'd be interested to know what you thought about it, particularly the position re. injections being unnecessary even for those with PA diagnoses. Is this possibly the source for all the problems lately with GPs withdrawing injections from people after years of being injected ?

Not sure why so many pages, think there must be a lot of blank ones but page 1 said something like 1/132 (can't remember the exact number now) and ditto subsequent pages.

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Hi Cherylclaire.

Think these are the sections you're referring to:

'Therapeutic schemes have not been definitely validated,24,25but everything seems to indicate that oral treatment is both effective and sufficient, including in the case of pernicious anaemia'


'it should be reminded that the parenteral route is decreasingly justified in the majority of aetiologies of vitamin B12 deficiency and that, as mentioned earlier, oral treatment has been found to be both effective and sufficient, including in the case of pernicious anaemia'

A number of problems with these claims...(and I also note that they say 'therapeutic schemes have not been validated πŸ˜–πŸ˜–).....

1) as far as I have been able to find out, the research these claims are based on measured the uptake of B12 from high dose oral forms of B12 (thought that 'flooding' the gut with high doses enables some B12 to be absorbed passively throughout the gut).

However, the researchers simply measured the serum B12 level following treatment.

And it's already been proven that serum B12 levels are no indicator as to the of efficacy of treatment.

So, the research did not undertake any clinical evaluation in terms of symptom relief and return to health and well being.

2) even given that, the only oral B12 supplements licensed for use in the UK are 50mcg cyanocobalamin - so GP's are not able to prescribe the high doses of oral B12 that would be required (even if we accept the papers hypothesis as 'true')

So, if GP's base treatment on this hypothesis and the currently licensed low dose B12 oral tablets, (and I think some may be doing), then that's not good news.

However, some people do seem to manage with high dose oral therapy (good idea to give loading doses first) ...but not many and certainly not everybody...but nobody currently knows why this is the case (much more research needed).

And in the UK, injections are still currently the recommended treatment for PA - most especially where neurological symptoms are concerned.

To introduce the possibility of high dose oral therapy into potential treatment regimes, the U.K. would first have to licence high dose oral B12 tablets for prescription.

(I've tried high dose sublinguals and nose drops, neither of which worked for me).

And of course, the problem then would be getting the medical profession to recognise that 'one size' does not fit all, and that oral therapy may be suitable (and suit) for some, but not for others).

The PAS's points out that if oral therapy becomes part of treatment guidelines (it currently isn't), then patients should be given a choice, in terms of treatment options, since what works for some, may not work for others (more on the PAS website about this).

So...much more research needed here...my personal opinion is that there's not currently enough research to make the statement that oral therapy works for all...and then impose an oral regime of therapy on all PA or B12 deficent patients.

Like you, I think it's a dangerous retrograde step to make that assumption, based on current knowledge.

Oh, and, I note your welcome comments to Blinkysmom about all the cancer references in the paper...so as not to frighten...

The paper's main focus seems to be about where high serum B12 levels are found...when no B12 supplementation has taken place.

It's not making a hypothesis that high serum B12 levels from injections can cause cancer. (Though if cancer is present or develop while on B12 treatment, then B12 can cause cancerous cells to multiply a little more quickly - one of the cases where B12 treatment has to be monitored with care - but not stopped...obviously πŸ€”πŸ™ƒ).

And high MMA can be caused by B12 deficency too - so a result with a very high level does not mean that cancer is present (high levels can also be caused by other non-cancerous conditions too).

Sorry if all the cancer stuff was a bit frightening πŸ˜–πŸ˜–...

Think one of the problems here is that there's so little research about functional B12 deficiency, we sometimes have to come at it 'sideways' through other research papers...

Will add this information if I link to this paper again elsewhere - we deficients have enough to worry about without having to worry about cancer too) πŸ˜– πŸ˜‰πŸ˜€πŸ˜€


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Thanks for the reply. Being honest, Foggyme , I have found this whole thing a bit frightening.

It started, for me, with a GP telling me that cancer of the bowel first needed to be eliminated, as a warning was coming up on her screen when she typed in my symptoms. Later, another GP was concerned that MMA level could possibly be due to cancer: I can see why she thought that, having now read this paper. She was the one who diagnosed Functional B12 deficiency, and got it confirmed by sending bloods to St Thomas'.

I can see why ruling out cancer first is a priority, I can also see that diagnosing certain cancers at an early stage is difficult, and that if high MMA and/or high B12 levels (without supplementation) are to be useful markers, that needs more research. I think one of my haematologists believes B12 to be carcinogenic because of her having misconstrued articles such as this one.

You are right about the dearth of information on Functional B12 deficiency- this, plus a lot of very confused thinking by haematologists, makes real progress difficult.

Restoration of self, not a stagnating host of symptoms, is what I'm after (still). Never believed I had cancer.

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Hi Cherylcalire. Yes, it is all very frightening. For me, the most frightening thing is the woeful lack of knowledge by many doctors - as in the haematologist who has obviously misconstrued papers like this one - so think you're right there, I think πŸ˜‰πŸ˜–. And there are many other too.

So sorry that you're still a stagnating host of symptoms.

I'm confounded that your doctors have identified an issue with B12, ruled out other possibilities for your symptoms...and still,won't treat you according to the guidelines! (If I remember correctly, they won't give more frequent B12 injections than monthly).

Here's something thinking on that (working from memory):

Your neurologist refused to prescribe injections more frequently than monthly because didn't want to,prescribe outside of BNF guidelines. Well, wonder if he's aware that the BNF guidelines for those with neurological symptoms are (after the loading doses) injections every other day until no further improvement (it's the second item down in the BNF so doctors rarely read that far).

Note: BNF refers to this regime as treatment for PA. But...whether you have PA or not is a moot point. The treatment for PA is treatment for the B12 deficency it causes...so the treatment for B12 deficency (whatever the cause) is the same as the treatment for PA...B12 injections.

You could,point out to your GP that the neurologist wants to remain within the BNF guidelines...and that those guidelines prescribe every other day injections for those with neurological symptoms...like you.

Incidentally...as far as I can determine from currently available research...the treatment for functional B12 deficiency is frequent high doses of B12...so having the neurological regime of injections would deal with any potential functional issues too. (Two birds with one jab).

Don't think you'd be unreasonable asking your GP for this again (it's what you should be getting anyway).

You could also point out that you were improving (if I remember rightly) when on every other day injections...and then went backwards when the injections were changed to once monthly (something that happens to many people).

And you could support it with the American haematologists review paper which states (at the very end) that some people need more frequent injections...that some self-inject very frequently...and that there's no reason to discourage this (i.e. High frequent doses of B12 are safe and work for many people).

Another thing...when you were on every other day injections and improved, this could be considered a successful treatment trial...so why stop it...especially in view of the following decline you suffered πŸ˜‰.

If your GP will again not follow the BNF, BCSH and NICE guidelines for those with neurological symptoms, then the only option might be to try self-injecting with B12, on the basis that you're following guidelines that are already in place πŸ˜€.

Having the extra B12 is perhaps the only way to find out if this is the answer.

I'm so cross that you're left as a stagnating host of symptoms when the one thing that might just make a difference is consistently refused...even in light of guidelines which state that you should have it.

I long to hear of a restoration of self (what a wonderful way to put it)...and thank heavens you don't have cancer (good that they checked but why oh why can't they treat the obvious (diagnosed) condition whilst ruling out other possibilities.

So frustrated on your behalf...keep.posting updates...fingers crossed.

Take care xx


Not long now till my (final?) haematology appointment, where MRI brain scan and genetics lab results etc. will all come together and I will know where this is all heading. This is what I keep telling myself when very symptomatic - not long now: one more week.

As you so rightly remind me, Foggyme , I can always self-inject to ensure guidelines are followed correctly (!) if everyone else is too afraid. First, I want to see this through now, just to make sure it's not anything else.

I will of course let you know the outcome. Thanks for all the support x


Grief Cherylclaire...it's been a long haul, hasn't it!

As you say, not long now πŸ˜‰.

Thinking of you and keeping everything crossed and yes, really keen to hear how you get on.

Take care xx

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I've just noticed that the NHS web page on B12 and folate deficiency anaemia includes a section on Functional B12 Deficiency - nhs.uk/Conditions/Anaemia-v...

Some people can experience problems related to a vitamin B12 deficiency, despite appearing to have normal levels of vitamin B12 in their blood.

This can occur due to a problem known as functional vitamin B12 deficiency – where there's a problem with the proteins that help transport vitamin B12 between cells. This results in neurological complications involving the spinal cord.


Thanks for that, but this is confusing to me, fbirder, because the first B12 blood test I had (Feb 2016) DID show a deficiency- and this was why I was being injected and monitored originally: it was only because I was getting worse not better once on 3-monthly injections that MMA was tested and found to be raised (although plasma B12 was over 2000) - this was in October.

Anything I have found, and there isn't much, talks about functional B12 deficiency with NORMAL B12 blood levels as does the quote above. Nothing I have found yet gives GPs advice about on-going treatment, which could present problems.


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