Pernicious Anaemia Society

Why is B12 not rising???

A quick question...anyone have any thoughts. My autistic daughter has pernicious and has been taking methylcobalium sublingual drops daily since September 2016( we are in the states). Had blood work done recently and her B12 level was only 428. I expected it to be off the charts with her getting it daily? She is compound heterozygous for the MTHFR gene, so is also taking methyl folate and B6. Any thoughto???

16 Replies

It could be that she is converting it and using it up or you may find that using methylcobalamin in spray form works better than lozenges because it breaks up the molecule more and this helps .


If the spray did 'break up the molecule' then that would be a bad thing. Breaking up the molecule is another way of saying 'degrading'.

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The reason that someone thought of putting methylcobalamin in spray form was in order to do just that ! B12 has a large molecular size so it would make sense . "Degrading " is another completely separate issue .


Sorry, but that is just nonsense. If you break the B12 molecule into bits then you no longer have B12. And there is no way the bits could pass through the mucous membrane then reassemble into B12.

The reason for using a spray instead of a lozenge is that a spray will maximise the surface area covered with the B12.

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Maximise the spray area ? Reassemble into b12 ? What on earth are you talking about ?


Maximise means - to make as large as possible. Making the area of mouth that is in contact with the B12 solution will maximise the amount that gets absorbed.

You said that the spray "breaks up the molecules". That means, to work properly, the molecules must be put back together again, or reassembled.


so what you are saying is that if you break up a cake into slices its no longer cake


nanodroplets !


B12 is not a cake.

Cut a cake into 100 pieces, it still taste the same.


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I am saying that if you break up a car it's not going to work until you put it back together again.

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If your daughter has PA then it's unlikely that any sublingual stuff will deliver the amount of B12 she requires. Get your doctor to give her B12 injections.


Using the sublingual methylcobalium drops that you put under the tongue and hold there for 30 seconds. It is suppose to absorb directly through the thin lining.


Hi Lorstor. The absorption rate from sublinguals is very low (about 1 - 2%) and it's not yet clear how much is absorbed sublingually and how much is absorbed from passive absorption through the gut.

If your daughter started with a very low B12 level (and it sounds like she might have) then at that rate of absorption it will take a considerable amount of time to raise her B12 levels.

Here's some information about the use of sublinguals:

b12researchgroup.wordpress.... (Serious Caution Note about the use of Oral and Sublingual B12 Supplements)

In the UK, pernicious aneamia is treated with IM injections of B12: an injection delivers 100% of the B12 dose, the first six being given on alternate days to bring B12 levels up quickly - then followed by a regular regime of injections.

You could:

A) Consider swopping completely to treatment via B12 injections.

B) Consider a course of six loading doses to bring levels up quickly, then use sublinguals to try and maintain her B12 levels. This would have to be monitored very carefully to ensure that levels did not fall again - which they may well do.

C) Change to high dose sublinguals (5,000 - 10,000) - but keep in mind that although this sounds a large dose, the absorption rate is still low and probably not adequate for anyone with a low level of B12.

About B12 levels: once treatment has commenced and B12 levels raised (people on injections have high or very high levels - mine are routinely over 2000) serum B12 levels cannot be used as a measure of the effectiveness of treatment. The only way to know if the dose and frequency of B12 is sufficient is by the effective relief of symtpoms. the face of it someone could have a high (or even very high) B12 level and still suffer the symtpoms of B12 deficency, and hence the potential for neurological damage (because the symtpoms have not been effectively treated so damage is still occurring).

You say your daughter is autistic so I can understand that having injections is something that may difficult for her (and for you too). However, if communication is also a difficulty, it might not be easy for you to determine if symptom relief is taking place.

As you cannot know this from her serum B12 level the safest way to ensure the she gets sufficient B12 for effective repair to take place is ensure that her B12 levels are kept high and do not drop. (High levels will do not harm - low ones will).

It's possible that if you stay with the sublinguals or even have the loading doses and then return to sublinguals, her B12 levels may not be maintained. And having a low level risks the potential for possibly irreversible neurological damage.

In the UK, an intensive regime of IM injections is the only form of treatment recommended for anyone suffering neurological symptoms and people with PA and / or B12 deficency are treated with IM injections also.

If your daughter has neurological symptoms her serum B12 level needs raising quickly (while low, damage occurs).

People sometimes take oral tablets, sprays, nasal drops or patches for a 'boost' between injections (different methods suiting different individuals). For some they work (as a boost to keep symtpoms at bay between injections). For some, they don't work at all.

It sounds like your daughter is absorbing a little from the sublinguals - but not very much (she's been having them for a while). I think I would urge you to consider using B12 injections if this is possible given your daughter's autism, especially if communication makes assessing symptom relief difficult.

I'm not sure how much you know about the B12 deficiency caused by PA so I'm going to copy some links in at the end of this reply. It will enable you to understand more about serum B12 levels and the connection (or not) to effective treatment and....oh a whole host of other things about B12 deficency. Whilst the guidelines for treatment are UK guidelines, the principles remain the same and may help you make a decision about how best to proceed with your daughter's treatment.

Good luck to you both, pop in anytime you need any help or support, and let's us know how you get on. 😄

LINKS TO INFORMATION AND GUIDELINES (BNF B12 Deficiency: Hydroxocobalamin Treatment Regimes)

pernicious-anaemia-society.... (PAS Symptom Checklist) (British Society Haematology (BSH) Guidelines: Treatment of B12 Deficiency and Folate Disorders) (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)


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Foggyme, thank you so much for all the detailed information. I am reading through it all now! And I will definitely have questions I am sure.


No problem Lorstor. Normally I would just say...go for the injections.

But I recognise that you may have unique circumstances that might make this difficult. But the catch twenty two is that those circumstances mean that injections are probably best 😖

Post away any time...a new post is always best because more folks will see it and you'll get a better response (older posts slip down the page And get lost in the mists of time).

Take care 😄


You need injections for your daughter. It's not absorbing or the strength from orals is too low even if it's high strength.

Looks like that's the problem.


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