Pernicious Anaemia Society
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Variable effect of B12 injections

My mother was diagnosed as b12 deficient approx 2 years ago (I was diagnosed Dec 2016). She was never tested for PA - I tested negative but understand there are often false negatives.

My mother had 2 weeks of alternate day loading doses of hydroxycobalamin and 3 monthly thereafter. Her initial symptoms were quite severe wobbly legs and tiredness, to the extent that she could barely walk even short distances. For several weeks the GP diagnosed this as post viral even though my mother had not been unwell previously. Eventually I suggested that she ask for a blood test for b12 and reluctantly the GP agreed. The level came back at 135. Since starting the injections she has sometimes improved but at other times the injections seem to make little difference. She also always starts to feel more wobbly and tired at around 6 - 8 weeks after an injection.

Is it usual for the effect of the injections to be variable? Do wobbly, shaky legs count as neurological symptoms as if so according to NICE guidelines she should be having 2 monthly injections I believe? She has asked for more frequent injections but been denied. She is 78 but usually very active and this is impacting on her daily life and she is starting to feel very down. What can I do/suggest to help her? She also has hypothyroidism but this is under control believe. I wondered if she should push to be referred to a haematologist. I would really appreciate some advice please

5 Replies

We read often here and on Thyroid UK that Low B12 and Low thyroid do go together. It may be a good idea to take a look at your Mums latest thyroid results - they often only check the TSH - which needs to be around 1 or under. The FT4 and FT3 need to be in the higher part of the range. Sadly the T3 - the Active hormone - is rarely checked and people are denied full health. The conversion from the T4 tablet into the Active T3 hormone is more efficient when levels of Ferritin - Folate - B12 - VitD are optimal.

It is is more than likely your Mum needs more regular injections of B12 and you are of course correct about neurological issues requiring a more regular protocol. Lots of information under the heading Pinned Posts - to the right of your Post - or scroll down if you are on a phone. Also the excellent posts from Sleepybunny and Foggyme

Were the Folate levels also checked ? Good levels also needed as it works with the B12 in the body.

Your Mum could supplement between injections with say 5000 mcg B12 Jarrow Methylcobalamin - available from amazon - they also do a 1000 mcg lozenge. These are absorbed under the tongue to avoid any gut issues. There are also sprays and patches which could help.

Hopefully your Mum will soon be back to good health ....



I have never heard of PA or B12 deficiency as being in any way genetic...

Sounds to me like Marz (see other replies) is right. She gets "wobbly" after 6-8 weeks because she badly needs another B12 injection to replenish her reservoir (which I am told is in the liver) from which many other systems, including neurological, balance and such draw energy.

As I have been led to understand, B12 results in a kind of low energy current (analogy) that activates so many of our bodily systems it is no surprise if a deficiency of it negatively affects different things in different people. Think of the B12 reservoir as a battery that makes everything in your car work; if the battery runs out of juice, nothing works until the battery is recharged from an outside source. First the lights begin to dim, then the car won't start at all; and that is "pernicious" anemia.

In the U.S. we also need a prescription for injectable B12 serum, but there is no limit set on how often we can self-inject (except our personal budget). Perhaps you could look into getting the serum and needles and injecting her yourself more often. All of the authoritative literature says overdosing of B12 cannot happen because all excess is rejected as waste liquid.


UDEE. Just a quick comment...PA is an autoimmune condition and these often run in perhaps not specifically genetic (though there might be genetic elements that I am not aware of)...but there is a clear evidence that it does tend to run in families (as do other autoimmune conditions - diabetes, thyroid problems, lupus etc.).


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Hi julesr21. Hello and welcome. I agree with Marz. It sounds as if your Mum is not getting enough B12, and I think that there's been a missed step (or two) in her treatment protocol.

If she had neurological symptoms when she was originally diagnosed with B12 deficency she should have been given an intensive course of B12 injections, referred to as the neurological regime. Her B12 level was very low (a severe deficency) when she was diagnose, so I'd be very surprised if she didn't have neurological symptoms.

Neurological regime, as follows: 6 x loading doses followed by an injection every other day until no further improvement in symptoms (sometimes for many months)....and then eight weekly injections (though this is not enough for some - but that's another story). (I'm going to include a symptom list below for you to check - you might find that your mum - and you - have symptoms that you didn't even know were symtpoms).

I think the first 'missed step' is the lack of every other day injections until no further improvements (and the next, the lack of eight weekly injections after that).

Not many GP's know about is neurological regime. It's in the GP's prescribing bible - a called the BNF (your GP will have a copy on her/his desk). It's the second item down so they will have to read further than they usually do. (Copy included in the links below for your information).

Ah ha, your GP may say - she hasn't been diagnosed with PA, and that for,people with PA. Wrong. The treatment for PA is the treatment for the B12 deficiency it causes...and B12 deficiency can also have other causes so...whether she has PA or not is a moot point: the treatment for PA, for the B12 deficiency it causes, and for B12 deficency due to any cause, is the same: B12 injections.

Also - your GP may mistakenly assume that if your mum's B12 level is now within the normal reference range, then she's getting enough B12...and doesn't need any more. Wrong. All the guidelines state that once treatment with B12 has commenced, no further testing is necessary (unless checking that levels are not too low). This is because B12 levels inevitably go up - simply because high doses have been injected - the levels in the blood are no reflection on how effective the treatment is - the only measure of this is symtpom relief - GP's should always treat the symptoms, not the serum B12 levels/test results - all the guidelines state this. Not many GP's know this. 😖😖 might be difficult (because GP's are sometimes ill-informed and may take a little persuading),would be a good idea to try educate your GP into prescribing the every other day neurological regime to see if this improves your mum's health - it will do if she is being under-treated for B12 deficency - and B12 is not dangerous, toxic, or harmful (as some doctors mistakenly believe) so not treating her could potentially do her more harm than treating her. (I'm leaving document links below that will help you to put together some evidence about is so that you can take it to your GP, for discussion. It's a good idea to highlight the relevant bits - your GP won't have time to wade through it all. And also make a bullet point list of all your arguments before you go (linked to evidence) to keep you on track. If you could take another person with you (in addition to your mother) this may help - and if that person has also read your evidence and can jump in to,support your arguments, if necessary - even better. GP's are often more attentive and less hostile when there is a witness in the room. Sad, but true.

GP's are most often completely unaware of the neurological havoc that under treated B12 deficency can wreak on the body. So...go to the pernicious aneamia society website (library section) and download a document called subacute degeneration of the spinal cord...this outlines the damage that can potentially occur when B12 deficiency is not treated or under treated - especially if neurological symptoms are present. I'm not suggesting your mum has this but rather that showing this evidence to her GP may work to sharpen his/her thinking (and prescribing) a little! Especially if you ask them to confirm that your mum is not at risk of this because of her neurological symptoms (and in the light of the failure to follow the neurological treatment guidelines when she was diagnosed) 😉.

It may help to book an appointment with a named GP, then, before the appointment, write a letter to that GP outlining all your concerns - including supporting evidence from the links below / the information about subacute degeneration of the spinal etc. and make the request for the neurological treatment regieme in writing. Also ask that if they decide to withold this treatment, please can they explain their reason for this decision, I writing - and provide medical evidence to support that decision (they won't be able to - there isn't any).

Also a good idea, at the end of the letter (if this is the course you choose) to say that you sincerely hope they will take the time to review the evidence enclosed prior to the appointment, so that you can make best use of the time available. What you're really doing is forcing them to read the evidence because it will become part of your medical record - so they will be accountable.

In an ideal,world we should all be able to pop along to our GP's, chat about our health concerns, agree tests to be done, share evidence and jointly agree on a treatment plan..oh how I wish...

So...having said all that, you know your own GP and will know,how best to make your own approach...🙃

Also - while I'm here - people with B12 deficency often have absorption problems and consequently suffer from other deficencies, which can make you feel very rough indeed 😖. So..your GP should be keeping an eye on (blood testing) the following (especially in the continued presence of symptoms):

Folate: B12 and folate work together so if folate is deficenct or low in the reference range, the body cannot utilise B12 properly. Check folate levels.

Ferritin (one of the markers for iron deficency anaemia - often present with B12 deficiency). Check ferritin levels.

Vitamin D - a common decency in we deficients - ask GP to check vitamin D.

A note about blood tests: GP's often say blood tests are normal when they're not. Bumping along the bottom of the reference range (or indeed, the top) Is not good enough to for people with B12 deficiency - many GP's don't know that. If you want to get copies of blood test results (you're legally entitled to these) and post the here on the forum, we can help with interpretation.

Anyway julesr21...that's just a few tips to get you started. B12 deficency is quite complex so if you have any more questions, or you want more help educating and persuading your GP, then post again...lots of lovely folks here to pop along and help (but oh my, wouldn't it be so good if it wasn't necessary 😄).

Good luck to,you and your mum...let us know how it goes...her come the links:


b12researchgroup.wordpress.... (Serious Caution Note about the use of Oral and Sublingual B12 Supplements) (BNF B12 Deficiency: Hydroxocobalamin Treatment Regimes)

pernicious-anaemia-society.... (PAS Symptom Checklist) (BSH B12 Deficiency / PA Diagnostic Flowchart) (British Society Haematology (BSH) Guidelines: Treatment of B12 Deficiency and Folate Disorders) (NICE Guidelines Treatment of B12 / Folate Deficiencies) (UKNEQAS B12 Treatment Alert, Neurological Symptoms and Risk of Subacute Combined Degeneration of the Spinal Cord) (Problems with Serum B12 Test) (Testing B12 During Treatment) (Misconceptions About B12 Deficiency – Good to Know Before Seeing GP) (B12 Treatment Safety / Long Term Treatment for neurological symptoms) (B12 Deficiency: Neurological Symptoms Can Present Even When B12 is ‘In-Range’ and Without Macrocytosis (large red blood cells) or confirmed PA Diagnosis) (B12 and Intrinsic Factor) (B12 & Nitrous Oxide Contraindicated)



Just wanted to say a huge thank you to you all for your comprehensive replies particularly Marz and Foggy. I feel like I now have something to go forward with. I will come back at some stage and let you know how we got on.


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