Pernicious Anaemia Society
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Vitamin B 12 low

Hi all,

I am after some advice. I went to the GP's a few weeks ago and asked them to run some bloods as I was finding I was having to sleep for 8-10 hours a night and I was still exhausted the next day. At weekends I find I have to cat nap just to get through the day. I am also suffering from dizziness, cold hands and feet and pins and needles in my hands and feet, irritability, mood swings because of the tiredness and I have also had my neck spasm twice in the last 6 weeks. I also have brain fog and forgetfulness. I am 33 years old. I thought I was either anaemic as I have been in the past or had thyroid issues as these run in my family.

The test results all came back clear except for my vitamin B12 which came back a little low at 154ng when it should be 160ng.

My GP has ordered further tests another b12 serum test and intrinsic factor test and said they will only treat me if these are abnormal. Does this sound right to you? From the reading I have been doing anyone who shows sympomatic symptoms of B12 deficiency should be treated and If it is not treated can lead to further complications.

I am trying to educate myself so that I can be my own advocate and fight for treatment. Any advice anyone can give me would be much appreciated.

Thanks in advance

10 Replies

Hi Carlygeorge ,

Welcome here! You will help your self a great deal if you read up as much as you can about PA/b12 def.

Re:"My GP has ordered further tests another b12 serum test and intrinsic factor test and said they will only treat me if these are abnormal. Does this sound right to you? From the reading I have been doing anyone who shows sympomatic symptoms of B12 deficiency should be treated and If it is not treated can lead to further complications."

It is usual to do further testing and to need to have 2 results showing a B12 def before treatment is started.

Being negative for IF antibodies just means you are classed as IF neg PA as that test is notoriously unreliable, see:

I hope you will get treatment soon and you will feel a lot better (in time),

Kind regards,



Actually if you are based in the UK the treatment isn't really following guidance - which is to treat on the basis of symptoms rather than results as there are various problems with the accuracy of Serum B12 as an indicator of deficiency


Summary of BCSH guidance on cobalamin (B9) and folate deficiency

NICE guidelines on diagnosis

Second clearly states that test results need to be interpreted with care as people can show strong clinical signs of B12 deficiency without this being reflected in results that are outside the range.

B12 deficiency is NOT anaemia - anaemia is one of the symptoms of B12 deficiency, though the guidance by NICE is far from clear on this point. Anaemia is not always present/obvious - particularly if your folate levels are good.

The fact that you have neurological symptoms - the tingling - is worrying - left untreated neurological damage will become permanent.

B12 isn't an expensive drug - though the fact that GPs tend to insist that it is administered by a nurse tends to add enormously to the cost of treatment but it's still cheap compared to the consequences of treating you for permanent neurological damage.

Please don't accept the answer that you won't be treated unless the other result comes back normal - argue about the neurological symptoms, the fact that the test is known to have limitations and that the BCSH guidance is to treat on basis of symptoms not test results and you clearly show a good range of symptoms

Fuller list can be found here.


It might be a good idea to give this a thorough going through and take it with you to your next appointment.

Hope you manage to get the treatment you need.


Hi thank you for your replies. I am quite concerned. I am in the UK, London to be more exact and I have private health care through work - are there any other tests I should insist on? Are my GP's doing enough. The anaemia I suffered from in the past was iron deficiency Anaemia. I have found out my grandfather has to have B12 shots but we are unsure as to why.

I know my red blood cell width was ok however my red blood cell count was the exact figure of the lower limit and so they have said I am not anaemic at the moment.

What I am finding confusing is the different ranges for vit B12. I have read that if it is below 200 you are deficient but my doctor said I am only just deficient at 154 as their lab range starts at 160?!?

It's all so very confusing


Hi Carly,

Yes its very confusing that different labs use different units and ref ranges for "normal" levels of serum B12.

As the serum B12 test is very crude and you are in London I recommend you go to ST Thomas and have the active B12 test done, it costs only £18,- and is a far more precise test of how much B12 is actually available in your body in the form it needs. If your active B12 is marginal then test MMA, more expensive. Both are far more early indicators of a possible B12 def, and with your family history it would be wise to test further. Get as many test done before you may consider self treatment as its so much better to get a diagnosis and then the right treatment now, than to skewer future results by self medicating.



More places to have the active B12 test can be found in this link, see:

Kind regards,



You are showing typical neuropathic symptoms, which is typical once the B12 levels drop below 500.

All mammals are born with 2000mg in our system, which gradually decreases as we get older.

Contrary to what most GPs believe is an acceptable level - A completely healthy person should have at least 1400mg of b12 in their system.

Once your B12 drops below 500mg, you will start to experience neuropathic symptoms.

B12 is responsible for many important factors in the body, including your DNA and your central nervous system.

Depending on how long your levels have been left to get too low will depend on whether or not the damage is likely to be permanent.

My advice to anyone experiencing neurological problems, is to start self injecting every day until symptoms disappear.

This is what GPs should be doing, instead of just looking at levels in the blood.

This is not an accurate enough test because, even if you have an acceptable level in your bloodstream, it doesn't mean it's always being absorbed by

everything in your body that needs it.

A blood test by itself can, and often does, give a false positive result.

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If you have private health care insist on urinary MMA and serum homocysteine as these build up in B12 deficiency so will help confirm.

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Gosh you are all being so helpful - thank you so much :)


Some basic B12:

B12 is used by the body for a number of key process which include

a) healthy cell reproduction: so lack of B12 will lead to deformed blood cells

it also increases the chance of cancel.

not certain but suspect that things like hairloss/thinning are probably related to cell reproduction not going well

b) maintaining the insulating lining around nerve cells

hence the link to numbness, tingling, insensitivity to pain and hypersensitivity to pain

there may also be a link in to muscle weakness (nerve signals affected)

problems with balance

one theory around problems with incontinence is that this is in part due to this affecting the autonomic systems

I have also seen it hypothesised that the 'sighs' may owe their origin in part to affects on autonomic systems related to breathing - sygnals just not getting through right so you think you aren't getting enough air

other possible outcomes are dementia

memory problems are common though that's a long way off dementia and caught early enough the damage to brain cells can be reversed.

c) recycling a couple of waste products such as MMA and homocysteine

homocysteine can lead to deposits building up in blood vesels and hence is associated with cardio-vascular problems like heart-attack and strokes.

B12 deficiency may be caused by lack of B12 in the diet (eg strict vegan as it is only found in animal products)

However, the mechanism by which most of your B12 is absorbed 99% - is quite complex and delicate so there are a number of things that can go wrong including

I) autoimmune responses that either kill off the binding agent (Intrinsic Factor - hence the IFA test), or the parietal cells in the ileum that do the absorbing (PCA test - even less accurate than IFA which is why it is not generally done these days)

This is pernicious anaemia in the proper sense ... but the name is a bit of a misnomer because although anaemia occurs it isn't the anaemia that makes it fatal

ii) changes in acidity in the stomach - gets lower as you get older - and the absorption process needs a certain level of acidity

so, gets more prevalent as you get older - CDC website in US has banner headline that 1 in 31 over 51 will be B12 deficient - though estimates actually vary and I have seen estimates of well over 20% of the population over

ironically another consequence of lowering stomach acid levels can be acid reflux which is then treated with drugs that lower the acidity level more and make the situation worse ....

iii) genetic abnormalities affecting the ileum - which mean that parietal cells for example can't work properly

iv) gastric surgery affecting the ileum

worryingly people who have gastric surgery aren't warned about this possibility and GPs often don't pick up on it

v) drug interactions - there are a number of drugs for a variety of conditions - including anticonvulsants, anti-acids, pain-killers, metformin used to treat type 2 diabetes - that have the side effect of suppressing the uptake of B12

Pernicious Anaemia seems to have genetic links which means that having a relative with the condition increases the statistical probability. It also has a tendency to occur with other autoimmune problems like thyroid and diabetes and as there is a huge overlap in some of the symptoms one condition may be treated and the B12D is left untreated. It is quite frequently misdiagnosed as a whole range of conditions including ME, MS and dementia.

There is a high correlation between blue eyes and premature greying and pernicious anaemia - though I believe premature greying also correlates to thyroid problems.

The body does store and recycle B12 but it does so via the liver and bile draining into the ileum so if you have an absorption problem this mechanism is compromised.

People vary a lot as to how much B12 they need and some people will exhibit no signs of B12 deficiency but have very low levels of Serum B12 whereas others may have strong clinical signs but a relatively high serum B12 - around 500 downwards. In Japan people are generally treated if levels are below 500.

It can take years and even decades for a B12 deficiency to progress though its progress does tend to accelerate as the recycling mechanism gets less and less efficient.

A lot of people experience a quantum leap in symptoms as a result of surgery where nitrous oxide has been used as this oxidises a key part of the B12 molecule meaning that your body can't use it.

You need both B12 and folate (B9) for a lot of the key processes mentioned earlier. So a folate deficiency will make B12 deficiency worse.


Just to add, its probably best to avoid any supplementing with B12 until you've had all these tests done otherwise the results may be invalid.


I have not been taking any B12 but thank you for the heads up. I just called the GP to get my results but they only have half of them and just said tell patient awaiting other results before a decision is made about next steps - I am taking that to mean by B12 is still low and they are awaiting on the intrinsic factor - I have read everything you guys have sent me so I am ready for a fight - if needs be


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