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Pernicious Anaemia Society
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Colonoscopy!!!! Yikes

Hi guys, first post on here. I am a 53 yr old female who is hypothyroid, diabetic, anaemic and have a b12 deficiency. My GP has been doing bloods and had me on iron tablets to get my iron levels up but has now said I need a colonoscopy to find out why I'm anaemic, the anaemia and b12 deficiency were picked up about 2 years ago when I had a stroke. I went into a drug trial after the stroke and they did a very comprehensive range of bloods and picked this up, once discharged from hospital I was meant to go and see my GP but ended up having a phone conversation (GP didn't feel it necessary to see me) where he just poo pooed the anaemia and b12 and said if I was still worried to go back in six months and have a blood test! To be fair to me I had just had a stroke and completely forgot all about it, I was feeling so wretched I was exhausted aching brain fog muscles feeling like lead, you all know the symptoms. Everyone kept telling me " you are still recovering from the stroke" and in an effort to feel better I increased my thyroid meds as the symptoms are very similar, my blood sugars were good so I knew it wasn't that. It was only when we moved house in January last year my new GP did some "" welcome to the surgery bloods" and picked up the anaemia, the light bulb went off and I remembered my conversations about the b12 deficiency, so they checked my b12 started me on the loading doses and now I'm on every 12 weeks. I'm trying to get them every 8 weeks as I really start to flag by week 7. I'm rambling now but original question why the colonoscopy? An as a last note, I have been gluten free and dairy free for a long time as these upset my tummy, bloating gas and diarrhoea. Also if I hadn't moved house my diagnosis would probably still be undetected, when you have someone who has a complex medical history why don't they routinely check for associated conditions? Very frustrating nhs

19 Replies

I was hospitalised for anaemia this time last year. They suspected it was due to a bleed in the GI tract. A gastroscopy showed no bleed, so they did a colonoscopy, which also showed nothing. By then my iron levels were OK, so they decided it must have been a short-term bleed. The good thing was that the gastro registrar was the one that got me tested for B12 deficiency.

However, I suspect the colonoscopy may have exacerbated the B12 deficiency. I was offered, and accepted, gas and air (Entonox) during the procedure. This is a 50:50 mix of oxygen and nitrous oxide - and the latter can severely deplete B12 in people with borderline deficiency - tipping them over to the point where severe symptoms can occur - adc.bmj.com/content/85/6/51...

When I have to have one again I think I'll skip the Entonox. I believe that other methods of sedation are available, but I'd rather be awake (sounds strange, but I really found it fascinating to watch it on the monitor). I would mention your B12 deficiency and possible problems with gas and air.

The procedure isn't very painful, just be prepared to lose all dignity (they pump your colon full of air - which has to escape somehow). The worst part was the laxatives you have to take the day before - phew!


What meds are you on for the diabetes? Metformin is well known to interfere with absorption of B12.

A colonoscopy can help to clarify what is causing problems with absorption - and you seem to have a lot of absorption problems.

99% of B12 is absorbed in the ileum so one thing they are likely to do is check what is actually happening in the ileum - any sign that cells there have died - which would be the result of pernicious anaemia - and autoimmune problem in which the body attacks the absorption mechanism in the ileum - either the cells or the binding agent that allows the cells to absorb.

Howver PA is only one of the potential causes. Others include drug interactions (hence the query about metformin), gastric surgery affecting the ileum, and even acidity levels in the gut falling ... given all the problems you are having with food and your age the last seems quite likely. To make things worse the symptoms of low acidity have a huge overlap with high acidity and frequently get treated with drugs designed to lower acidity making the problem even worse.

As Fbirder says - avoid nitrous oxide - its a super-oxidiser of B12 and will render what B12 you have useless.

Unfortunately B12 is 'only a vitamin' and tends not to be part of the syllabus that most GPs have followed - or if it is gets a very small mention. The symptoms are wide ranging and frequently mistaken for other problems - if you have any diabetic neuropathy then you really need to push that up the agenda as there may also be neuropathy due to the B12 deficiency going on - and if you have neuropathy then the treatment should be shots every 8 weeks ... though it may be difficult to get GP to recognise that as a possibility - though does sound as if the one you now have is a bit more on the ball and open to considering the options properly.

There is also a tendency to assume that once you have one answer you have them all so it is only when problems have become very bad that other options get looked at.

The treatment for a B12 deficiency (unless caused by diet) is injections which are for life whatever the actual cause. Unfortunately most of the guidelines out there talk about investigating the causes, and they tend to focus on PA as the cause. People get caught up in a load of testing when the treatment is actually going to be the same - which is a bit difficult to understand on one level - especially when a lot of the tests are known to be a long way from 100% accurate - most struggle to reach 50% accurate.

The only advantage I can see is related to genetics and the likelihood that other members of the family will experience similar problems ... but given how many people struggle with getting diagnoses when there are clear family histories even this seems to be clutching at straws.

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Hi gambit..... Well there is a massive family history for hypothyroidism and diabetes, I am on metabet a branded lactose free gastro resistant metformin and forxiga for the diabetes, and liothyronine for the hypo thyroid. But do take omeprazole for acid, I have recently started vitD supplements as well as these were 57 i think the lab range was 50- so I am very near the lower end of that. Also after I had the stroke I was started on copidagrel and a statin, I had never heard of b12 before the stroke and to be honest even when I asked the nurse just said " oh your dr will prob give you some shots" I was more worried about the anaemia as I have never been anaemic before. It was a nightmare as when symptoms overlap you look to what is already being treated hence my increasing my thyroid meds. When new GP did bloods she told me to decrease thyroids as they were too high. So now I've gone under active and they are increasing those now! I was too embarrassed to tell her I had increased them myself. But my thyroid and diabetes are both autoimmune conditions so it's also likely that the b12 is PA or no?



very true that auto-immune problems occur in groups, so quite possible it is PA.

Are you diagnosed as type 2 diabetic? There is a third type of diabetes - MODY - that is onset later in life and is frequently misdiagnosed as type 2 but depending on the sub-type responds to different medication. It's really closer to type 1 and is also a dominant gene which would fit with a strong family history.

sounds like a lot of your meds aren't helping the situtation and you could probably do with a thorough review.

Referal to a gastro is probably a good idea - hope they know something about B12 - and hope they can go through your meds and may be sort out something that is going to be less of a problem.


I don't think endoscopic examination of the ileum will help in diagnosing PA. Although B12 is absorbed in the ileum it is higher up the GI tract that the problems happen. Lack of intrinsic factor means that the B12 that does reach the ileum cannot be absorbed (the transporter protein locks onto the IF to carry B12 across the gut wall).

However, they may want to do a gastroscopy as well. Biopsies taken from the stomach and duodenum can give good indications about gastric atrophy (combined with B12d its a good indication of PA) and coeliacs.

Many people who are sensitive to wheat aren't actually affected by gluten. Instead it's carbohydrates called FODMAPs that cause the problem.

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Well I had gestational diabetes with my last pregnancy and was told at the time that I would prob get it later in life. ( mum was 55 when she was diagnosed) but also my thyroid packed up roughly the same time.... I took 8 years to get a diagnosis by which time I had put on 7 stone in weight was completely inactive and clinically depressed, the weight gain and inactivity brought the full blown diabetes on much Sooner age 39.

My GP said that you no longer have a consultation anymore just go and have the colonoscopy. So I will mention the b12 deficiency anything else I could ask?


55 does sound like type 2 rather than MODY diabetes - there's a variant of MODY that runs in my family but that usually manifest between 30-45 - I didn't inherit the gene but my mother did.

Sounds like you have probably been on metformin for over 10 years + so it may have been a factor in getting you to where you are.

The anaemia may be related to the B12 deficiency or it may be something else going on in the gut. Do you know what type of anaemia you actually have - B12 deficiency is generally associated with macrocytosis (red blood cells rounder and larger than normal). If you have an iron based anaemia that would tend to make the cells smaller and so may have delayed the diagnosis of B12D if it was done purely on the basis of macrocytosis. Macrocytosis isn't always among the first problems to materialise with a B12 deficiency - I don't have anaemia though I've had neurological and neuropsychiatric symptoms for decades prior to diagnosis.

On the whole it sounds like your GP is probably doing the right thing which is starting to look at what is happening in the gut and if there is anything there that may be causing the absorption problems you are having.


What are Fodmaps?


apparently it stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols ... bit of a mouthful :)

This article might help




Some links that might be useful

Nitrous Oxide


Drugs that can affect B12 uptake. (Some drugs can affect folate uptake)


See "Drug induced causes" section

"I'm trying to get them every 8 weeks"

Do you have any neurological symptoms? My understanding is that B12 deficiency sufferers with neuro symptoms should get injections every 2 months.

See Documents listed for treatment details

1) BNF (British national formulary) Chapter 9 section 1.2

All GPs will have access to BNF. Local libraries may have a copy. Copies can be bought from a popular online retailer.


2)BCSH Cobalamin and folate Guidelines

UK document that came out in 2014, easy to find on an internet search. Sadly some GPs may not be aware of this document. I was told the NHS should be following it. I gave a copy to my GP. Found page 29 a diagnosis and treatment flowchart helpful.

3) patient.info/doctor/pernici...

This link contains similar info to BNF in Management section.

Symptoms lists



See Symptoms checklist

The PAS are helpful and sympathetic. Lifetime membership costs £20.

01656 769717

useful books

Could it be B12?: An Epidemic of Misdiagnoses

by Sally Pacholok and JJ. Stuart

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

by Martyn Hooper

Other useful websites




Thank you for the links, the martynhooper blog was very interesting to read, I am convinced that my mum is b12 deficient with symptoms apart from the aching joints fatigue aching muscles etc she is very forgetful and confused. She has been sent for dementia testing but the. Dr reckons there is no dementia. She said she asked the surgery to test her b12 at the last blood test and they said "it was normal" I'm going to get her to ring and ask for the numbers after reading that blog. She is 72 and has, not only a terrible diet but has been on metformin for 20 years. Thank you


It is useful to ask for a paper copy of the blood test so you can compare future results. Well done for looking after your Mum.


I had quite a similar experience stroke, angina that was caused by anaemia picked up b12 issue. they did a colonoscopy to check the cause of anaemia even though i had large red cells associated with pernicious anaemia. the colonoscopy showed diverticulosis but nothing to explain the anaemia. i had a camera to check my stomach that found mild stomach atrophy. this was associated with the PA. I was worried by the tests but they were ok. . i use boost b12 spray in between injections. it helps me dont think it helps everyone. I hope you better soon love susan x

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I have been reading through the info and links kindly sent to me by sleepy bunny, I am devastated to discover b12 deficiency can cause recurrent misscariage!! Followed by infertility. Surely that would be one of the blood test that is done in early pregnancy. my daughter is a midwife so I have just txt her and asked the question. Has anyone had recurrent misscariage prior to diagnosis and treatment of b12 deficiency? I know this is a very personal question but I have been to torturing myself since reading the article!


I had a colonoscopy (and gastroscopy) to try to establish why I was b12 deficient. My GP said I probably didn't have PA as my blood tests (Intrinsic Factor, anti-parietal cell antibodies) were negative. As I had a long term history of diarrhoea (until then presumed IBS due to food intolerances), he referred me to a gastroenterologist to try to establish what else could be causing the B12 deficiency. The gastroenterologist told me that inflammation due to Crohn's disease and colitis/microscopic colitis could cause malabsorption of b12, and the colonoscopy would identify if I had that. They didn't find anything, and put the malabsorption down to 'fast transit'. Good luck with it!


Sounds like me...... Years of persistent diarrhoea don't eat wheat or dairy am now trying to cut all yeast from my diet. I am sick and tired of feeling sick and tired!!


I know how you feel! I get on ok with wheat and dairy - but I don't get on with most insoluble fibre / fodmap foods. I cant eat onions or garlic at all (they are the absolute worst offenders); a lot of other vegetables cause problems, like broccoli, asparagus; I can only very rarely have wholemeal bread; can't have wholemeal pasta, brown rice etc. I also get diarrhoea after eating anything too fatty, like oily fish, batter, ice cream etc. For a while I thought dairy foods caused a problem, but now realise it's the fat in certain dairy foods that causes issues for me, rather than anything intrinsically dairy. Basically, I eat a low residue diet, with bland food - white bread, potatoes, white fish. It makes healthy eating a challenge - but then I can't imagine 'evacuating' healthy food a few hours after eating it and not absorbing any of the goodness is terribly healthy either. Not to mention the loss of electrolytes from diarrhoea. If I stick to my low residue diet I am generally OK, but always take Imodium if I'm going out. I hope you get some answers!



"and they said "it was normal""

I learnt from experience to always get paper copies of all my blood test results. Surgeries may make a charge for this.

What I was told was normal, face to face or over the phone was not always normal when I got paper copies.......

Some people find it helpful to get copies of blood test results going back a number of years. I find it helpful to track changes in my blood results over a period of years.

I concentrate on my blood results for B12, folate, ferritin, full blood count.

The full blood count(FBC) can have useful clues as to the possibility of B12 deficiency. High MCV and high MCH can indicate the possibility of macrocytosis. My experience is that GPs pay more attention to high MCV results than high MCH results.

Low B12 and/or low folate can lead to enlarged red blood cells (macrocytosis). Low iron can lead to small red blood cells (microcytosis). If a person has both conditions its possible that MCV may appear to be normal.

A blood smear aka blood film may show both microcytic and macrocytic cells in the same sample.






"but has been on metformin for 20 years"

I have read that metformin can deplete B12 in the body.


See "drug induced causes"section.

"my daughter is a midwife "

I wonder if your daughter is aware of the effect nitrous oxide, a constituent of "gas and air" used as pain relief in labour, can have on B12 levels?


I believe some of the problems I have are partly due to prolonged exposure to nitrous oxide during a long labour.

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Well cutting out the yeast seems to be helping, especially with the gas!!! My poor long suffering husband is very pleased. As for my mum I spoke to my dad last night and he is going to make an appointment for me to go in with her. I will make some notes and print off a list of symptoms and use the nhs 1-10 scale for severity of symptoms, I am guessing getting b12 shots is something that could be done privately if I get no joy from her GP?


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