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Pernicious Anaemia Society
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B12 serum monitoring


My Gp has retired and the new GP has requested I have a blood test prior to renewing by B12 prescription.

I am diagnosed with PA just from them ruling out other things and because my levels keptdropping quickly even after loading doses.

After several years of trying various frequency of injections I have found that every 3 weeks keeps be going. My former Gp allowed me to self inject and was happy to treat my symptoms.

My question is that if I have a b12 serum test it is surely going to show it is sky high given I am injecting every 3 weeks. I was under the impression that once you are supplementing the b12 test would be useless other than showing you how quickly your body can get rid of it. I am concerned that the new Gp will say i don’t need them as often as my serum test is high. I do not want to make myself poorly just improve the point as I am really unable to function.

Is there any written guidance to back up that this is unnecessary? Any help really appreciated.


10 Replies

Hi Julie74 I would have thought that if your notes say you have P.A (or even if it doesn't) there will be a record of your fluctuating B12 serum test results to refer back to plus the current "accepted" frequency of injections that should be sufficient to convince your doctor that, irrespective of the pending test results, your current treatment should continue.

I am not a medically trained person but I've had Pernicious Anaemia (a form of B12 deficiency) for more than 46 years.

I wish you well.


Try this NHS document that recommends no further testing...



Pity your old doctor retired.

Your new doctor does not seem to have read the NHS guidelines which state that after treatment no more blood tests are needed - obviously your B12 will be sky high.

Unfortunately many GP's use this as an excuse to stop injections.

I suggest you show your GP the NHS guidelines (I see fbirder has given you the reference, thanks) and hope as clivealive says that your current treatment will continue. Otherwise I guess it's buy your own B12, luckily you already know how to self inject.

1 like

You could try putting the following in writing to the surgery?

The latest BMJ research document summary below demonstrates that treatment for PA is for life, as do other guidelines so, hopefully GP will probably be able to access and read the full document (behind a paywall).

At the bottom of page 4 ' under 'Parenteral Treatment' :


"Parenteral treatment

"Data from randomised controlled trials and observational studies for parenteral treatment are lacking; however, the expert consensus for standard treatment in the United Kingdom is to begin parenteral treatment with intramuscular hydroxocobalamin. This bypasses the possibility of the debate about whether the treatment will be adequately taken, absorbed, and metabolised. Standard initial treatment for patients without neurological involvement is 1000 μg intramuscularly three times a week for two weeks. If there are neurological symptoms then 1000 μg intramuscularly on alternate days should be continued for up to three weeks or until there is no further improvement.4 25 In irreversible cases, for example, pernicious anaemia, the treatment should be continued for life. "

Also at the bottom of page 4 ' under, 'How is Response to treatment assessed'), it outlines that, once treatment is given, blood levels will inevitably increase but it is the clinical condition of the patient that is important:

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

Good luck Julie


My own blood tests after injections started were always well over range at >2000ng/L, by which I'm assuming that 2000ng/L is as high as they go in that laboratory. I've never had my B12 injections stopped, just reduced to what they believe guidelines are telling them: no more than 1 every 2 months. None of the specialists I have seen like it that I self-inject every other day, but it has got me back to work and allowed me to improve enough to have a relationship with partner, friends and family...... and improvement is still continuing after 10 months. No reason given for B12 deficiency or more recent Functional B12 deficiency.

If you have a PA diagnosis, it cannot be removed as there is no cure for Pernicious Anaemia. The B12 injections are there to stop you deteriorating: if your levels are high, it's working ! There must be plenty of evidence for that, even for a busy GP.

Very best of luck. Tiring, all this, isn't it ? Hopefully you will only need to educate your GP once!


Thank you for your message

Yes very tiring. She insisted on checking my levels but has promised not to reduce how often I have them. She was very nice but I think she feels I am hyper-anxious looney. I was quite stressed so think that’s how I probably came across. Oh well at least she is t going to reduce them.

Best wishes



May I send you a PM? irina


Yes of course


Typing it now.


My GP and nurses have seen me crying/ shouting/ storming out/ pacing up and down/ unable to understand them at all, so I wouldn't worry too much : they know "ill" when they see it, and they know "recovery" when they see it too, even when it goes against what they might have been taught or advised. Even when they can't admit it out loud.

Deterioration is very scaring. Choosing to deteriorate in order to (re-?)educate consultants or GPs about the far-reaching effects of B12 deficiency seems like utter madness.

Compare the lists of B12 deficiency symptoms written by and for the health service with those gathered from research questionnaires filled out by people diagnosed with PA and living with it. A lot missing there* .

Why do they never start by looking at nails, hair, tongue, etc.?

* "Hyper-anxious looney" would be one of the items missing from the list !


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