Pernicious Anaemia Society
14,620 members10,416 posts

low B12

Hi , so I went to my GP because I'm always tired , never wanting to do anything and very forgetful , I would wonder around my house looking for something but I couldn't remember what. it was bad, so I asked my GP to check my b12 and iron, my iron was fine but my b12 was only 131 , so my GP told me I needed a shot once a month and in 3 months it should be normal. I had an appointment with my GI doc and he was looking at my file and said my b12 was fine. and then an other doc at emergency told me I should be getting a shot weekly. so 3 docs and 3 different opinions . so I talked to my GP again and he was sure once a month was fine.. So I go for blood work 4 months later and my b12 only came up to 141 and my GP is baffled as to why its still low . I have celiac and that runs hand in hand with b12 so I know why it was low but I'm not sure why it hasn't came up to normal yet with the shots as its bypassing my stomach altogether . can anyone help me understand

8 Replies

You should be getting a Loading dose. NHS would say that's 5 shots over 2 weeks. Really you need one every 2 days until your symptom improve & your levels are right. Keep them over 800.


Probably because you need them more often. Maybe look at the list of neurological signs and symptoms on the website below - if you have any then you should be having B12 shots on a much more regular basis until things improve. Also taking a GOOD B Complex keeps all the B's in balance. You need Folic Acid or Methylfolate to bind with the B12 to keep it in the body longer....

Docs are rarely up to speed an diagnosing and treating B12 deficiency. Have you had the tests for PA ? One auto-immune issues often accompanies another. You do not mention a range for the B12 - but it looks VERY low ! The range starts at 500 in Japan - as mentioned in the first link I gave you. Please do read as much of the above as possible - information enables you to ask the right questions of those Docs.

There are many VERY knowledgeable people on this forum - and they will be along soon with their advice.

Am off for my weekly B12 injection at the local Pharmacy ! I live in Crete !

1 like

Marz makes a good point about looking at neurological symptoms. Do you know the reference range for B12 your area? In my area, your B12 result would be considered low.

Has your GP checked the treatment guidance in their copy of the BNF (British national Formulary)? Patients with neuro symptoms and B12 deficiency should have an injection every two days until they stop improving then an injection every two months.

All GPs will have access to a copy of the BNF.

Has your GP seen these documents?

Google "BCSH Cobalamin and Folate Guidelines"

The PAS (Pernicious Anaemia Society) can be very helpful. if you leave a message they will get back to you. There is a useful library section on the website.

pernicious-anaemia-society.... 01656 769467

Other useful info

Books "Could It Be B12" by Sally Pacholok, Pernicious Anaemia ; The Forgotten disease by Martyn Hooper. Living with Pernicious Anaemia by Martyn Hooper

"GP is baffled as to why its still low"

People need good levels of folate and iron for the uptake of B12 to be good. Some medications can interfere with uptake of B12. Have you had any surgery involving nitrous oxide recently?

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If you are getting shots then coeliacs isn't a factor in what is happening with your blood levels because you are not absorbing B12 through your gut anymore.

Post gives me the impression that you aren't UK based and that you are probably being treated with cyanocobalamin.

Couple of things may be going on

a) once a month may not be enough for you - people loose B12 at different rates and the higher the amount in your blood the higher the rate of loss as well - so it may just be excreted in your urine.

b) people respond differently to different forms of cobalamin and it may be that cyanocobalamin isn't the right form for you

MTHFR might be a problem - though that would probably show up as a high level with no recovery as your body wouldn't be able to convert it to the form that is used at the cell level.

c) do you know if your folate levels are okay - you need folate to process B12 - it can get depleted when you are being treated because the body starts to use up your reserves and if these aren't being adequately topped up you will become folate deficient and then your body won't be able to use the B12. Again, this is probably something that would result in higher levels in blood with no improvement in symptoms

There are probably other explanations but a) seems the most likely of the ones above.


Hi . I know the feeling. Mine was only discovered when I got angina and heart problems. Better now. I saw GI no coeliac but they were really helpful, they found out why I had it (mild stomach atrophy and diverticulosis) and gave good advice. I did not eat dairy products but found this helped 600 last time from 323. From a low point of 20 with iron at 8. I did suffer some damage but feel better no more heart issues, still low ferratin and a few balance issues but i did have a stroke.. Did you have the loading dose of b12 for two weeks..Hope you get the answers you seek and return to good health soon x

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Please join the pernicious anemia/b12 on f.b. You need other things like folic be optimal for the injections to work. Pernicious means deadly. Under treatment is common. They saved my life...


I have b12 shots for close to 10 years and its still not normal, I find reports from specialists inconsistent and not helpful. Non-one has told me why my B12 level have not changed I know you need to look at your mcv blood results. Sorry I cannot be more helpful, but my forgetfulness has detoriated apart from forgetting things, I forgot familiar words as well. I believe its all linked.


thank you all for the info . I recived the shot once a week for a month now every 2 weeks for 2 months then I got to have it checked again, if it still does not come up then I got to see a neroglist . and I forgot to mention I'm from Canada not the uk .


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