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Pernicious Anaemia Society
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Opinions please on b12 and anaesthetic

Hi everyone,

I am due to have surgery soon, and it could be as much as 12 hours. I asked my surgeon to check my b12 along with other bloods he was ordering.I`ve only had one b12 injection in past 5mths, so was surprised when he came back with a level of 600. I asked him the range he didn't reply but said you have enlarged red cells ah that will be the PA and everything else is fine no anaemia. So my results don't match my symptoms :-(

Anyone have an opinion on optimum levels prior to lengthy anaesthetic? I have a supply of b12, just arrived from Germany so I can boost it up if I need to.

I have tried for years to get neurologists to listen about my b12 symptoms. They just smile at me. At my last visit a few weeks ago when he smiled I retorted you doctors just don't understand PA. He didn't smile at that! He thinks I am in denial that my MS has become progressive and I am blaming PA. I do believe that when you have an illness such as MS everything gets labeled "ah that will be your ms".

Sorry ranting a bit,kind of went off subject.

Thank you in advance for any advice. xx

27 Replies

a) the only anaesthetic that I'm aware of that causes a problem with B12 is nitrous oxide. This oxidises B12 making it non-viable for use in your cells.

b) you need to make sure that the anaesthetist doesn't use nitrous oxide.

c) no point in loading up on B12 prior to the operation if nitrous oxide is being used as it will be oxidised in the operation. You need to use it after the operation.

MS is a possible misdiagnosis of B12 deficiency. But it is also possible to have both things going on at the same time.

Did he say that you do or you don't have enlarged red blood cells - if you do have enlarged red blood cells then that means your cells don't have enough B12 at the moment. Normal level doesn't apply after loading shots and many people require much higher serum B12 levels post loading shots so 600 could be too low for you and if you have macrocytosis again it is definitely too low.


The large red cells could also be caused by low folate.


Hi. Thank you for your reply. He said I do have enlarged red blood cells. Which I thought strange as Ive had pa for many years..The ms neurologist uncovered it after running tests.

I had bloods done 4yrs ago that came back low in folate GP gave me 5mg daily for 1 month, same bloods came back with hypothyroid but GP at the time said its borderline so I wont treat just monitor bloods every 6mths.

I am feeling so bad with symptoms its making me wonder how on earth Im going to cope and now cancer treatment on top of everything else.


not surprised you feel awful if you are also hypothyroid and not being treated. Suggest you post on TUK about the hypothyroidism


you really need to get a full blood count done along with folate to rule out folate deficiency

Any chance of moving to a new doctor

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Hi I have thyroid uk in my hub as both my daughters are hypothyroid.

Recently moved to another area,not any experience of my new gp but I am going to call in tomorrow and get them to use nhs system to get blood results from hospital.

Also I had bloods done at neuro clinic after I asked why do they never check thyroid levels, will chase that up too. Honestly you have to push hard for any test.

Thank you again.


Hi, I received a letter from my neurologist. He didn't give me any thyroid results,so I'm assuming they were in range. He checked folate and has said it is very low and has written to my GP to prescribe.

The patient leaflet says folic acid is contraindicated for patients with cancer,which I have. This got me looking up on pubmed and other research papers. It seems to be the relationship between folate and B12 in the replication of cells is the concern,as some tumours are folate hungry.

I will of course discuss with oncologist and consultant next week. It leaves me worried that if I cant supplement then I'm left to really struggle with the symptoms,which are very much debilitating on top of everything else.

Following my surgery I had very low blood oxygen levels and was kept on oxygen 24/7 for three days.Doctors constantly checked my lungs,but I feel it had more to do with the enlarged blood cells. They gave me blood thinning injections every day and that caused horrendous bruising.

Air hunger is much worse since I had op and isn't getting any better. I think this is one of the very low folate symptoms. During tests I had a chest CT and lungs were fine,and my asthma is well controlled too.

Seems I'm a bit of a mess. I have been struggling for ages. I think the next Dr that just nods and says yes I will flip!!

Thank you for your advice. xx


folate can interfere with some chemotherapy regimes for treating cancer and vice-versa and it is this that is more likely to be the reason why it is contra-indicated if you are being treated for cancer. With some chemotherapy drugs the effect is so pronounced that folate may actually be administered with the chemotherapy regime. You definitely need to discuss with the oncologist and consultant. If they advise that folate isn't being affected by any chemotherapy regime and wouldn't affect your chemotherapy regime then you need to get a prescription for folate from GP ... and if folate will interfere with the chemotherapy then you need to get advice from the oncologist/consultant on what is the best way of addressing the folate deficiency

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Link about nitrous oxide


If you're not already a PAS member, may be worth joining and talking to them, they may be able to point you to useful info on PA/B12 deficiency and anaesthesia.

PAS (Pernicious Anaemia Society)

Based in Wales, UK.


PAS tel no +44 (0)1656 769717 answerphone

"said you have enlarged red cells"



Full Blood Count and Blood Film



Folate Deficiency


I am not medically trained.


Hi. That was very kind and useful. Folate deficiency link, I noticed mentions glossitis,I have been in agony with exactly that plus ulcers etc.

Thank you x


Hmm, that's a difficult one, I've had numerous surgeries and I'm not sure what they used to keep me under sedation, however my bloods were taken before surgery and yep they asked when my next injection was due, so obviously they must of known that I was lacking B12, and ever since my last surgery in November time I feel I've ended up with more problems, constant belching, high pitch whistling/ringing in my ears, constantly feeling tired, and really bad sleeping patterns, I really think that this condition is to easily brushed aside, and even when I mentioned about taking long term omeprazole and having surgery to the nurse who gives the injection didn't know that this is a big factor in this condition, it makes you wonder how many individuals are walking around feeling totally drained, myself personally I think anyone over a certain age should be called in for a blood test especially if you have had long term stomach problems, and surgeries, I hope that you can resolve the issue and all the best on your future operation, thanks.


Hi Thank you for your reply and your regards re operation.

I know what you mean about brushing aside,so many have the attitude that its just a vitamin deficiency. Same with tinnitus ENT consultant said oh I don't do tinnitus. I am going drag myself into GP surgery tomorrow and hopefully get some results.

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Sorry to hear how poorly you are Kay. Ive been through cancer treatment myself so sending you get well wishes.

If it were me Id make sure you optimise your treatment, boosting your folate & B12 levels. I dont know what form of cancer treatment you are going to have but if its chemo it does knock the stuffing out of you....lol.

I also have hypothyroidism & key to this is making sure you get copies of all blood tests as like b12 the ranges are wide. Hopefully your GP will have got a ft4 as well as TSH done but these days the nhs seem to be leaning to TSH only. Very poor.

Its also worth talking to your Oncologist re your borderline thyroid as your Onc may prefer you are started on some treatment for your thyroid before doing chemo. This is not the tine for your GP to be taking a wait & see approach to your thyroid.

Thinking anout you.


Hi. Thank you for your kind wishes. I hope you are keeping well after treatment.x

I wont know about chemo/radio until after surgery. If I will be deemed fit physically to take it. The mdt team sat without my being there,so I have not had contact with Onc yet.

I got nowhere with GPs secretary today re bloods done at hospitals,where do they find these people? :-((


Yes the mdt do meet without you to discuss all cases. You will meet your Onc after your op. Worth mentioning your borderline thyroid to the surgeon.

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Hi Kay1986! I know what you mean about docs dismissing you and blaming the ms. My mom also has ms and I, along with both of her brothers are b12 deficient as is my son. None of us have been tested for PA as treatments started right away and for some reason no one cares to test around here. I’m from Ontario, Canada. She has had “ms” for over 20 years now. The best I could do was get her to take high dose sublingual b12. She immediately told me she felt a huge difference but unfortunately recently had a procedure and didn’t tell them that she doesn’t want nitrous oxide used. She has another surgery coming up and I will be trying to talk her into asking for no nitrous oxide or she will be getting injections afterwards. I just know her situation is definitely linked. I had a procedure and asked for no nitrous. They had no problem not giving it to me. Good luck with your upcoming surgery🙂

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Hi. Thank you for sharing experience. x

It is so very frustrating when doctors look no further for a cause. Tinnitus ah ms, uveitis ah ms the list goes on. I too have had ms for many years.My very first neurologist was very thorough he ruled out everything, lyme disease etc before making a diagnosis.

Ive had so much chemicals pumped into my veins for tests, I have radioactive injections to come before surgery too, this cannot be good for the body! xx


I had a 4 hour surgery where they didn’t use nitrous oxide & following the surgery I was on antibiotics for 2 months. Prior to this I had been on monthly b12 injections for two years and felt great. However, following the surgery and the long course of antibiotics I completely crashed and most of my b12 symptoms came back thus I would recommend that following your surgery you redo your loading doses! I really wished I had done it sooner than I did.


Hi. Thank you for sharing in your experience. x

I have my supplies and will definitely load up. Also taking folate from yesterday, not that I have enough time to make any difference before surgery.


Rant all you need to, I do it all the time. I find it's good to have somewhere, where people understand about PA \ B12 deficiency, to rant to, especially when GP's are so unhelpful.

It can be a lonely time if one has no support and no understanding. I have two friends and a private GP who understand, the rest, husband, family and other friends are rubbish.

So make the most of this very supportive, knowledgeable site.

PS Some anaesthetists know about PA/B12 deficiency and nitrous oxide, mine did, but do mention that you can't and don't have it.


Hi, Thank you for your supportive reply. x

I was a member of the PA society before it joined HU so Ive been around a long time :-)

It is very difficult and lonely when you are feeling so unwell,my husband died after a long battle with cancer,and yes I agree family are not so understanding.

I am very much hoping to meet anaesthestist in advance for a discussion as I have in the past due to asthma and cardio problems. Heavens I sound like I'm falling to bits :-) xx


I had very nice anaesthestists, my first knew all about the connection between B12 and nitrous oxide and thanked me for telling him, and made a note not to give me any. The second one didn't but said he would follow what the first did. I think the chances of getting one who knows, like my first one, are greater than finding a GP who does.

Dadvatar posted this lovely phrase a few months ago - sums my GP's attitude and others so well. "It looks like a duck, walks like a duck and quacks like a duck then it’s a chicken with mental health issues."

It still makes me laugh.

Let us know how you get on. Good luck with your op.


That one is cracking. I will remember that one :-))

I am keeping fingers crossed that I get a nice anaesthestist who will listen. Last one I had I told him about the carbon dioxide they pump into abdomen for laparoscopy left me in agony for 4 weeks, he promised to use the min that he could. And he did bless him.

Thank you again. xxxx

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Hi again. Thought to give you folks an update. Operation was a bit more than Drs anticipated. Spoke with anaesthestist prior to op he said nitrous oxide is old hat and as they do a lot of brain surgery its just is not used in this hospital. Following op I required oxygen 24/7 for 3 days as blood oxygen sats were very low blood pressure also very low. On 15min observations. Loads of blood tests and many Drs listening to lungs. Given shots of blood thinners every day. They were puzzled as to cause.

You may recall me saying pre op bloods showed enlarged red cells,I also had bloods done at MS neuro clinic. Neurologist wrote to me today to say test for folic acid showed a very low level. I am assuming enlarged cells and very low folate would answer the low oxygen sats. Also pretty slow healing.

I have read in the past that folate supplementing can cause some cancers to worsen and in some cases cause cancer if you have dna flawed as in a neoplastic cell mutation.

Another 2 weeks wait to hear if op was successful and get histology report.

Just glad its over and done.

Thanks again xxx

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Hi Kay1986

Welcome back, I'm glad to hear from you and that your op is done.

I had a quick look at articles for "folate supplementing can cause some cancers to worsen" but the ones I saw said " High doses of folic acid 'promotes growth of cancerous cells" so perhaps if one was just keeping folate up to a normal level, not overdosing, it would not cause cancer. I know nothing about this so hopefully someone with knowledge of this will reply.

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There is a chapter in Sally Pacholok's book ""Could it Be B12?: An Epidemic of Misdiagnoses" that mentions effects of nitrous oxide. Some of the case histories are heart rending.

Think nitrous oxide is also mentioned in Martyn Hooper's books.

"What You Need to Know About Pernicious Anaemia and B12 Deficiency"

Martyn Hooper is the chair of PAS (Pernicious Anaemia Society).

"Living with Pernicious Anaemia and Vitamin B12 Deficiency"

Has several case studies.

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"Same with tinnitus ENT consultant said oh I don't do tinnitus"

My tinnitus improved greatly once I got enough B12 (had to self treat for long time). When high pitched tinnitus comes back I use that as a sign I need more B12.

If you're in UK, there's the British Tinnitus Association


They don't seem to rate B12 as a possible treatment.


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Hi. When I first got tinnitus it was Deaf Society that gave literature etc. Mine has never improved just learned to live along side it. I said to my neurologist I have developed another sound,sounds like a petrol strimmer, keeps me awake. He told me to tell ENT consultant,whom isn't interested.Pass the buck it seems.

What I wouldn't give for silence!

Thank you once again. xxx

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