Pernicious Anaemia Society
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High Active B12

Hello I recently tested for Active B12, My result has come back at 120 when the range is 20-108. I have looked into what a high active B12 might suggest and am a little worried by the answers - serious diseases including liver disease and cancers. In particular there is mention of a type of blood cancer called a myeloproliferative neoplasm. Both my nan and my mum have this kind of cancer as it runs in our family. Anyone had raised active B12?

14 Replies


I'm sorry I don't know about myeloproliferative neoplasm.

Were you already supplementing B12 when you had the Active B12 test?

Supplementing prior to the test can affect the reliability of the test result.

I hope your doctors are looking into what caused the high result.


Sorry to hear that you are so anxious. I am assuming that you haven't been supplementing but are showing signs of B12 deficiency which is why you had the active B12 test.

As sleepy bunny says test results don't really mean much if you have been supplementing B12.

Elevated B12 is an early sign of problems that you refer to so the best thing to do - if you are concerned is to talk to your doctor and try to get a referral.

You have probably come across this article in your research but attach it just in case. The article is arguing that high B12 should be investigated to establish the cause - which includes the things you have listed - but could also include supplementation - which is probably the most common cause (my levels are always astronomic).

Some people experience the symptoms of a B12 deficiency when their B12 levels are high because they produce antibodies to the mechanism that transfers the B12 to the cellular level where it is used (TC11), so lots of it in the blood but very little getting through to the cell. One study referenced in the article suggest that this could be as many much as 30% of population (pretty sure I am one of them).

This abstract suggests that where there are absorption issues the best way of treating is actually very high doses of B12 (which is what I do)

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Hi Gambit,

Thanks for your response. I was indeed supplementing, but not with metyhlated B12 but with Solgar Vitamin B Complex which has 100ug of vitamin b12 as cyanocobalamin. I stopped taking these a week or so before testing.

I am very new to all this stuff Gambit. I tested because I had read some compelling stuff about the link between deficiency and anxiety and depression, which I am suffering from. I used the St Thomas's test cos I heard it was more sensitive. Alongside it I also tested for methylmalonic acid which was 110 (0-280).

One of the things I am quite confused about is whether the high levels of active B12 and in range Methylmalonic Acid mean that I am definitely not deficient or whether I still might not be absorbing because of the lack of something in my tummy - Is it called intrinsic factor.

If this is the case, what am I suppose to do next?



I realise the above post might look like I didn't read your links. I did. The fact my methylmalonic acid is in range is why I am asking about whether or not I still might be failing to absorb even tho my blood levels (not serum) of b12 are so high.


MMA is in range which implies that your body has enough B12 as it isn't building up - ie not above range.

The high reading is likely to be down to the fact that you were supplementing - 1000mcg is over 150 times the RDA. about 1% of B12 is absorbed outside the ileum so that would meant that in theory you are still receiving more than 1x RDA from using the tablets.

You would need to stop supplementing for a few months - 3-6 to get an accurate picture from any blood tests.

So, in this instance it would seem the most likely cause of the high result is the fact that you are supplementing.

However, as said earlier - if you are concerned then you should really try asking your GP for a referral and other tests to clarify the situation re the cancer.

Unfortunately B12D is far from being the only cause of anxiety and depression and your thyroid may be an issue as well - something that I really don't know a lot about - though you might be able to get some help on one of the thyroid forums ... as it's another condition that isn't particularly well treated (starting to wonder if there are any that are :)).


Thanks Gambit. It was 100ug not 1000mcg that I was supplementing which is according to Solgar 4000% of my EU RDA. I do hope that is what it is :-)


I think it probably was the supplementation - even though dose is only 40x RDA.

Malabsorption doesn't mean that nothing gets absorbed in the ileum just that it isn't very efficient ...

To know if you really do have a problem you would need to lay off any form of supplementation for a few months.

Does the supplement actually make you feel any better?



Sorry I also don't know about myeloproliferative neoplasm however, where did you get your active B12 tested? Did they comment on you being above the range? How was your serum B12 in comparison? Is your FBC okay/normal?

I had the Active B12 at St Thomas in London and mine was also 120 (they say anything over 70 is replete and good) (conversely my serum B12 was 254).

Hopefully, if you discuss your family history and result concerns with the GP they will give you a referral, it sounds like a haematologist would be a good starting point to get some further investigation.

What are your symptoms?




Symptoms are poor concentration and memory, anxiety and depression. I also have Hashimoto's, an auto-immune thyroid condition. I don't have any of the other symptoms like tiredness even though I sleep badly.

I too did the St T test. I asked my GP for that on the recommendation of Thyroid UK. I had to pretty much beg for it and my serum wasn't tested. I feel she would just roll her eyes if I asked for that to be tested now.




it sounds like it could be high because you were supplementing (although I wasn't and mine was also 120). I would get those results printed out from your GP to see if there is a range given. The Viapath website shows over 70 is okay:

You could also email Denise Oblain at St. Thomas and ask for clarification of your results. (I know they don't give out results directly but you could send an email saying you'd like some comment on the results being over the range and explain your family history?)

Can your Hashimoto's be causing your current symptoms? (I don't know about it - is it possible that any medication for that needs to be adjusted?)


I am sure others know lots more here than I do, but as I understand it (someone correct me if I am wrong). If you weren't absorbing the B12 properly and it wasn't getting into your tissues/being absorbed then your MMA would be high (above range), this would indicate a B12 deficiency together creating a picture with the Active B12 result.

At that stage, intrinsic factor is then tested to confirm Pernicious Anaemia (where stomach won't absorb the B12).


Re St Thomas; I had a bad experience with the private testing lab there. Might be a good idea to retest at another place.

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Bobbystranger - what happened? Did your results show differently elsewhere?


Yes I am keen to know also. I did PM but haven't heard back. What I have since found out which might be relevant to some is that:

a. The Pernicious Anaemia Society do not rate the Active B12 test (did I just waste my money? It seems so)

b. That I should have stopped taking my Vitamin B Complex much much sooner than one week before testing though I am still waiting for confirmation of this via Viapath. In other words, I might have a false result, which of course would be a huge relief.

I'll keep people posted because i know lots of you on here get your vitamin b12 tested. It seems I should have also had my Folate tested as the two work together.



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