Pernicious Anaemia Society
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B12 treatments

Hi, I'm new to this site. I have just been diagnosed with a B12 deficiency after having several 'seizures' like blanking out episodes over the last few months. My levels are 125. I am just waiting on results of another blood test to see if it's my stomach rejecting the b12 or if I don't eat enough. Personally I think it's my stomach as I eat red meat or fish every day and also plenty of dairy. Anyway, the doctor said I'm not very low so if I need the injections he wouldn't give me the loading dose. Is 125 too high for a loadinv dose? I'm feeling terribly weak at the minute and feel like I'm on a boat. Ideally I'd like a boost to my system. Has anyone not had the loading dose and been fine with it or on the tablets and they have made a big difference. I'm counting down the days until I start feeling better. Due my results back in 6 days!!!

7 Replies

Hi Niccitom,

Firstly welcome here! You should push for loading doses and not accept less, its not worth taking risks, its not expensive and getting the right treatment now will help you so much more than playing around with trying this or that.

If your GP is unwilling to give you the recommended treatment for a B12 def (positive or negative for IF antibodies), then you should insist on a referral to a haematologist, is what I'd do.

Perhaps read this (if you are in UK) and give a copy to your GP, it clearly explains what treatment is needed and that the serum B12 test on its own is of little value, but with your levels low enough to start treatment in line with BNF.


British Society for Haematology Guidelines for the diagnosis and treatment of Cobalamin and Folate disorders

"Recommendations  A blood film showing oval macrocytes and hypersegmented neutrophils in the presence of an elevated MCV may alert the clinician to the presence of underlying cobalamin or folate deficiency (Grade 2B)  Cobalamin and folate assays should be assessed concurrently due to the close relationship in metabolism (Grade 1A)  The writing group recommends adoption of reporting for cobalamin assay results in pmol/L (Grade 2C)  A serum cobalamin cut-off level of either 148 pmol/L (200 ng/L) or one derived from a local reference range should be used as evidence of cobalamin deficiency in the presence of a strong clinical suspicion (Grade 2B)  The report providing the result of a serum cobalamin assay should inlcude the following o The interpretation of the result should be considered in relation to the clinical circumstances o Falsely low serum cobalamin levels may be seen in the presence of folate deficiency or technical issues o Neurological symptoms due to cobalamin deficiency may occur in the presence of a normal MCV (Grade 1B)  Plasma tHcy and/or plasma MMA, depending on availability, may be considered as supplementary tests to determine biochemical cobalamin deficiency in the presence of clinical suspicion of deficiency but an indeterminate serum cobalamin level (Grade 2B) o Although plasma tHcy is a sensitive marker of cobalamin deficiency, plasma MMA is more specific o Both assays have to be interpreted in relation to renal function  Holotranscobalamin is suggested as a suitable assay for assessment of cobalamin status in a routine diagnostic laboratory in the future (Grade 1B) "



 Treatment of established cobalamin deficiency should follow the schedules in the British National Formulary (Grade 1A)."

I hope this helps,

Kind regards,


1 like

Note: references to NICE below assume that you are based in UK - other countries will have different guidelines.

If your serum B12 reading is 125 then that is a low reading for serum B12 and you should definitely be having loading shots. In Japan you would be treated with B12 shots if your level was below 500.

It may be just under what the labs in UK call the 'normal range' but significant numbers of people have strong clinical symptoms of B12 deficiency well into the 'normal range' and this really does seem to be a case where low is definitely low.

Not sure what tests your doctor has ordered but if it is IFA then you need to make sure he is aware that a negative result result doesn't mean that you don't have intrinsic factor antibodies as the test is not very sensitive - accuracy somewhere around 50% or less.

The NICE guidelines in the UK are treatment unless there is an obvious dietary lack of B12 (eg because your diet is lacking in meat/dairy/fish) with injections.

The consequences of not treating B12 early enough and aggressively enough can be serious (loss of quality of life and expensive to treat) because it can result in permanent nerve damage.

Some B12 is absorbed passively (ie not through the parietal cells etc in the ileum - about 1% - so in theory it is possible to flood your system with B12 taken orally but you need to be taking in at least 1mg - probably 5mg of B12 a day to get enough into your system to keep you going - and that isn't going to address the deficit that has built up. So, loading shots are important. From the way you describe your symptoms it sounds as if you are already showing some neurological symptoms in which case the correct treatment per NICE guidelines would be 1mg B12 intramuscular once every other day (which would equate to 3 x a week) until your symptoms stop improving followed by 1mg of B12 intramuscular every 2 months ... though lots of people find that the loading shots at that frequency are just far to infrequent and they need to find other ways of topping up

I don't know if you have anaemia of any sort but if you don't and your GP tries to tell you that you are in the early stages of deficiency don't listen to him. Many patients present with strong neurological and neuropsychiatric symptoms well before any anaemia occurs.

B12 is non-toxic and there are is no known downside to having high levels of B12. The treatment for cyanide poisoning is 5g of hydroxocobalamin administered intraveneously over 30 minutes - that is 5000 times the amount in a B12 shot.

It would be useful to follow up on your folate levels - B9 - as the body needs B9 to absorb and utilise B12 so if it is low it could affect your response to shots.

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Very good answers as always from marre and gambit. The bottom line is you need to insist on treatment. I found it helpful to take someone with me to GP. It is a scary time but you will get better on treatment. Good luck!


Have also seen it suggested that it is useful to send GP summary of points you want to discuss before hand - particularly any references that you feel they should look up - so they have some time to prepare.

In any case would be good to have brief notes of what you want to say worked out before hand.

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Thank you so much for your detailed replies and links, it has been most helpful. I'm glad the gp is checking to see why I have low B12 but it's taking such a long time I'm feeling pretty rubbish in the meantime. I am based in the UK and my iron levels were checked as well. These came back as normal. I have suffered with low iron in the past and its a very different experience this time.

I will push for a loading dose as you have recommended. The nurse I spoke to having my blood test said this was usually the norm so I'm hoping they will be happy to give it to me, if it is the injections that I need.

Thank you all



Wishing you good luck, it can take time (in my case 3 weeks) for antibody test results to come through, hopefully you will get the right treatment soon, and get on the road of recovery soon ! Marre.


I was diagnosed at the hospital when I was being investigated for something else, my levels were too 125. My GP refused to give me B12 as he said (like you) that my levels were not low even though the hospital said I was making antibodies to intrinsic factor.

So I left it, agreeing to have another blood test 6 months later, but after 3 months I felt so ill, tired and balance problems i went back to a different GP and she put me on the loading dose straight away, yes I did feel better, but now 3 monthly injections don't seem to be enough as I spend the last month being tired and am now going to ask if I can have them every 8 weeks.

I think the levels of B12 are not consistent between hospitals and GP's, that's where the confusion lies and frankly it's not good enough!


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