Log in
Pernicious Anaemia Society
17,184 members β€’ 11,892 posts

How will more frequent b12 help?

Evening everyone

I have PA. When my blood was last tested (mid July) it was 'high' at 2000 (the max they count I believe) so my nurse is questioning why I want/say I need injections every 6-8 weeks. (Because, I tell her ..., 'they help eleviate my symptoms!').

My question is why do more frequent injections seem to help me? If I've already got a lot of b12 in my blood, why does adding more help?

I know PA is about absorption, but if my levels are already high at 2000 Why does my blood/body need more if it isn't processing what's already there?

I think I'm trying to establish how I can answer her point of 'your levels are very high already'.

Many thanks in advance.


12 Replies
oldest β€’ newest

Hi Gilmarnay. You can answer your nurse by saying 'of course they're high...I've been having injections'! πŸ˜€.

GP's, nurses and even consultants very often make the mistake of thinking that once your levels are high, you don't need injections anymore. This is nonsense. And all the guidelines state that once treatment with injections has commence, there is no further need for testing B12 levels (because they'll always be high).

It's a bit like a car engine, you put the petrol in, the tanks full, then it goes down a bit, so you top it up. (a simplistic way of explaining, but you'll get the picture). However, it's not that simple. The level in your blood tells you nothing about what happens at a cell level. In addition, if you have PA, then injections are for life...and the frequency should be whatever you need to make and keep,you well (though the treatment guidelines are often inadequate any many people need more than than every eight to twelve weeks - but that's another story).

So why do more frequent injections help you...well, some people (many people) need much more than the current treatment protocols allow. Some people have to inject every day to feel well. Some bodies expel B12 more quickly...some people have more severe symptoms...we're all different. In short, the right amount of B12 is the amount that keeps the symptoms at bay (which is exactly what you are asking for).

So...have a read of the PAS pinned posts (to the right of the page when you log on)...these will give you more information which you can arm yourself with for discussions with your rather ill-informed nurse.

If they try to stop your B12 injections this is wrong. If this happens, please post again and people here will be able to offer more advice and support.

Incidentally, might be worth checking the symptom checklist on the PAS website. Don't know what B12 regime you've been on, or for how long, but if you have neurological symptoms, then you should be having more B12 (every other day until no further improvement, then eight weekly). But pop back if you need more advice about this.

Hope all goes well with the nurse (you could always direct her to the PAS website - they have a section for medical professionals, if she wants to educate herself - and help you πŸ˜€)

Take care X


Thank you so so much for your explanation. I feel a total idiot at the doctors because I can't explain (mostly because I can't remember what I've read) ,not to mention that I shouldn't be telling them how to suck eggs so to speak). I cry in frustration each time I leave my doctors. I'm sick of feeling like I'm begging, I'm sick of even having to try to explain. I shouldn't need to - I'm not the trained person in this doctor/patient relationship.

Thanks again for your help - it really is so appreciated.


You could also print off and show GP the latest BMJ research document (bottom of page 4 under 'How is response to treatment assessed' :


"Cobalamin and holotranscobalamin levels are not helpful because they increase with vitamin B12 influx regardless of the effectiveness of treatment,24 and retesting is not usually required, "

And just in case, the message of the importance of sufficient injections is ignored, here is an interesting Dutch link re. treatment.


I hope all goes well Gilmarnay.


Hi Gilmarnay. I'm so sorry that you're made to feel like this by your doctors and nurses. This is so bad, on so many levels.

Unfortunately, you are not alone in this. So many people here (in fact, probably all of us) have suffered and are suffering the same. This doesn't make it any better but at least you now know it's not just you.

And you're right - you shouldn't have to beg (and often be refused) a vitamin injection that costs about 55p. If you lived in Europe you could buy it over the counter and inject as often as you needed. Dogs get B12 injections every week, if deficient. Shows you how ridiculous the NHS approach to it all is.

Just know that there are many like you here on this site. And all ready to help and support as much as we possibly can. Just ask any questions you would like help with...and post a good old moan if it gets to much.

Take care x


Thanks Foggyme. Really appreciate the post.


I would suggest you cry with frustration while your with your doctor sometimes they dont understand how much its effecting you till you do.

I did that infront of my male doctor, many years ago, when i was put on antidepresents by a female doctor due to chest pains it was an easy fix from her point of view but it lead to bad panic attacks after 18 months.

It was when i changes my surgery that my male doctor could not understand why i was prescribed them but it took me to breakdown infront of him for him to realy understand the problems i was going through.


Just a thought Gilmarnay have you had your serum Folate level checked as this is essential to process the B12 you are having injected?


Believe I have had my feratin checked and 'all normal'. Must find out all my actual levels. Thanks clivealive.

1 like

Am I right in thinking that the serum b12 test measure both active and inactive B12, without distinguishing between the two. So presumably you could have a high serum b12 but a lot of that could be inactive.... is that right?


as Foggyme says the B12 serum test says nothing about what is happening at the cell level where B12 is used. In some people high serum B12 will kick off another auto-immune reaction which builds a dam in the blood and stops the B12 getting through to cells. The only effective way I have come across of treating this is for doses to be kept so high that enough trickles over the top of the dam to get through to cells - which may be one reason why some people need very frequent B12 - I use nasal spray to top up - if I didn't I'd be a pin-cushion because my dam is so high that my levels have to be ridiculously high for me to function.

One study implied that as many as 30% of the population have this response.

It is called 'functional B12 deficiency'.

Some people do find that smaller doses more frequently work better for them - not clear if that is this effect or something else going on though.

Couple of articles on functional B12 deficiency


(argument that you need to know the cause of high levels and they can be an early indicator of other conditions)



I have just come back from the doctor's, Gilmarnay. She was delighted to finally be able to tell me that I had 'functional B12 deficiency' (because of high MMA test results from St Thomas' *) and is now giving me loading injections until no improvement noticed (by me!) and then once a month..... this has taken a very very long time, a lot of dr's appointments, hospital appointments, etc. Please do not feel like an idiot at the doctor's. I also found it all overwhelming; armed myself with research, selected what would be most useful, then spent most of the appointment crying or trying to make sense of what she was saying, then forgetting what was decided by the time I got to reception. Take someone with you if you can: it made all the difference to me to have some support. If not, write to your doctor; often the appointments are 10 minutes which puts additional stress on you to get all your points across. I'm certain that this made a difference for me. You can choose a moment when you are feeling more lucid/ calm and take your time. The Pernicious Anaemia Society can help with telephone calls/ letters if you join.

*My B12 reading at the same time was over 2000- but perhaps they're all dead in the water!


Thank you so much. All these replies are so supportive. Hubby has offered to go to doctors with me but I've not done that yet. Trouble is my doc has just retired and now I've seen locus last couple of times - feels like starting again. I might write to doctor. This might help as I struggle to remember what I want to say. Thanks again.


You may also like...