Pernicious Anaemia Society

High B12 levels in a blood test

Hi All I am new here, My son is 10 and he has been struggling for few years with odd, what I can only describe as system-shutdowns. He starts feeling unwell, complains of strong stomach ache and sometimes headache. Than he has to rush to the toilet (not that he nececeraly uses it) where he is very shaky, as if he was cold, but complains that he is boiling up on the inside. Sometimes it is so bad that his teeth jatter. He gets very anxious during these attacks. This lasts for a hour or two and then he usually falls asleep with me cuddling him. Next day he seems fine. As he was getting progressively worse before Christmas, after not getting anywhere, I demanded blood tests to rule out infection or point to something else that might be going on. They came back very high in B12, double the recomended upper limit. After retest a month later they rose again. The doctors just reassured me that as everything else is normal it is none of the scary stuff. However high B12 is not investigated and is not usual so they are unable to explain or do anything. I am not happy with this I feel that my son may be at risk and that even though his symptoms are not frequent, they could point to something else that is wrong. I feel like I am banging my head against the wall and I have lost confidence in the pediatrician we are seeing, who has treated my son with Imigran for his headache, and recomended a psychiatric consult for anxiety, but will not investigate further his overwhelming High B12 levels. He has had his episodes since he was quite young, but as they are not frequent we are always just sent away to wait and see. I have read some of the blog here on High B12 and some of the things ring true, however I am very confused as to where to go further. I feel that all his mentioned symptoms might have a underlying cause. It was not untill I started reading up on low B12 that I realised that his memory also might be affected, we just always thought he is bit forgetfull. We are seeing a doctor on Wednesday and I would appreciate any helpful comments from you to work out a strategy how to get answers and treatment if needed. Thanks all for reading. Linda

9 Replies

I would push this with your Dr as this can be a sign of a blood disease. Perhaps don't mention the high B12 but approach from the symptoms point of view. List them and if necessary video the next episode.

Don't be put off, my grandson was told by a hospital dr he had anxiety and sent home with a referral to a neurologist but that Dr cancelled the appointment. So my daughter took him to a neurologist anyway and found he had Rolandic epilepsy so complained to the Hospital and the complaint was upheld. If you think something is wrong keep going and take pictures and videos to prove it. Insist on a referral to a paediatrician.


Hi Lindaand3.

First, I'm so sorry that your son is so unwell and that your doctor is not investigating the cause of the elevated serum B12 levels.

You're right, he should be.

The first thing to say is that elevated serum B12 levels can be present in something called functional B12 deficency. This a a condition where, for reasons not yet fully understood, vitamin B12 is not processed properly at the cell level, so serum B12 builds up in the blood and levels become excessively high.

Anybody with this condition will display all the signs and symptoms of B12 deficiency, which most medics fail to identify, since the assumption is that B12 levels are all must be okay ( Gambit62 is better at explaining this and will perhaps reply with a more detailed explanation if she spots your post).

Also, here's a link which will tell you more about this: (High Serum B12 Levels: Functional B12 Deficiency / Potential Underlying Conditions)

An MMA and homocysteine blood test can sometimes identify if a functional B12 deficency is present. These are not always freely available via GP's (though they can usually access them if they contact a haematologist or neurologist at one of the bigger hospitals - assuming you're in the UK).

FBC - this will identify if your son has macrocytic aneamia, often associated with B12 deficency (even in the presence of high B12 levels), folate deficency or PA.

Anti-IF antibodies, to check for PA, also a good idea. Though your doctor may say 'his B12 levels are too high to have this'....well, not if he has a functional B12 deficiency. Unfortunately, not many doctors are aware of this condition so you may have so erase arch on the Internet, become your own expert, and take along evidence to share with them (the link I've given to a paper above will give you a good start).

Also - you should also ask for folate levels to be tested. B12 and folate work together so if folate levels are deficient or low, the body cannot utilise B12 properly. Doctors will often say that folate levels are 'okay' or 'normal' when they're not. Levels need to be in the upper third of whatever the reference range is.

Your doctor should most certainly order these tests.

It's also worth noting that if you have autoimmune conditions in the family, then there is more likelihood that your son could also suffer an autoimmune condition - and PA (and the B12 deficency it causes) is an autoimmune condition.

It might be a good idea to read all the PAS pinned posts to the right of this page when you log on. They give lots of information about PA and the B12 B12 deficiency it would be a good idea to look at the symptom check list to see if you can identify any or some of your son's symptoms there. (But also note - B12 deficency can have causes other than PA). And keep in mind that he could still have a functional B12 deficency even though his B12 levels are very high.

It's going to be important for you to,know as much as you can about B12 deficency, since it will be a hard job convincing most doctors that this is a possibility (again, becase of the high serum B12 levels) and the lack of awareness in the medical profession, about functional deficency.

There are doctors who specialise in this at Guy's and St Thomas in London - if,you are in the UK it'd be worth considering asking your current consultant to refer you there, once initial testing has been completed, if necessary (we can give more information about that later, if needed).

It's also worth noting that anxiety and neuropsychiatric symptoms also occur with B12 deficency.

In the absence of vitamin B12 supplementation, elevated vitamin B12 levels can also be indicative of other underlying health conditions (for instance haematological conditions, liver disease)...and these should always be investigated via full haematological blood panels (possibly bone marrow tests as well) and comprehensive liver function tests. And there may well be other tests that need doing that I am unaware of.

If you search for 'elevated levels of serum B12' or 'elevated cobalamin levels' (or some such variant) on the Internet, you'll find more information about this - perhaps print some of the information and take it along to your appointment on Wednesday.'re right...your doctors should be taking this seriously, investigating fully, and referring onward for specialist advice.

Your doctor or doctors are wrong, very wrong. They should be investigate all possible causes for the elevated serum B12 levels. It's neither usual or normal. There will be a cause and it's up to them to keep looking until they find it.

Incidentally, if your son is diagnosed with pernicious aneamia (and there's no way of knowing at this stage whether that will be the case), if you join the pernicious anaemia society, Martyn Hooper, the Chair, is particularly keen on supporting and acting as an advocate for children who experience trouble accessing appropriate medical care and treatment.

Lindaand33...I'm so sorry that there aren't any easy answers here. All we can do here is try and point you in the direction of things to think about which may (or may not) help you with your doctor.

What I can say with absolute certainty is that if you have any more questions, or need any help...or just somewhere to have a vent or a chat...the are lots of lovely members here who will try their best to help both you and your son.

Take very good care both and I wish you the very best of luck for Wednesday...please let us know how you get on...and shout if you need anymore help.

And I'll end with a hug...because my goodness, I bet you need one x

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Foggyme , I couldn't get the link to work.

This is a link to an article from 2013 suggesting that high serum B12 should be investigated to establish cause as well as low B12

whilst one possible mechanism for functional B12 deficiency does seem to result in B12 being retained longer in the blood I've no idea how common that mechanism is and I don't think it is actually a causal factor in the initial development of a functional deficiency - just a complicating factor in treatment and possibly why using really high doses works better than waiting for levels in serum to drop.

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My fault Gambit62 ...or the auto-correct...inserted a full stop. Repaired and working. Here's the link again (in case you want a peek) 😄


same article :)

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Hi Foggyme, I thought I will reply directly to you as you might have the information I need. I am sorry that i have not been in touch sooner, however progress has been slow. On top of that my husband who suffers with cluster headaches has had a bad time with them, last couple of months, so everything seems to just take longer. We have now managed to get a referral to the Evelina Childrens Hospital in London for a appointment with the Haemophilia department. It seems that the Evelina is affiliated with Guys and St Thomas and I was wondering if it would be a good time to try to get in touch with someone at Guys to look into Leos case.

I seem to have a print out in all my paperwork from someone called B12 Turbo from this site that suggest contacting Denise Oblein, however I am unable to find the original post. They also suggested contacting DR D Harrington and his team, but did not want me to go ahead on my own.

The appointment in London is on the 23rd March and I was just wondering, even if it is short notice if there is someone at Guys that we might be able to see on the same day. (We live near Brighton and travelling up to London is not a easy task for us, especially with Southern Rail problems)

Hopefully we won't get the same reply as before "not medically relevant".

As always, thank you for your help and if you have any advice for how to proceed further or if you have any suggestions for contacting Guys and St Thomas please let us know.


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Hi Lindaand3...just replying to the PM you sent me...


Hi everyone, thank you so much for all your kind replies. It seems that I have some reading to do :). I will be back to let you know how we got on. Thanks so much again.


Hi guys, just a quick update, thanks again for all your help, I had a good read and we had a chat with our doctor. He will be getting back to us within the next couple of days, hopefully with a plan of action... Thanks everyone for your responses and special thanks to Foggyme for your kind words. Bit more waiting but hopefully we are making baby steps... will keep you posted.

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