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Pernicious Anaemia Society
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Active B12 test results

Hi everyone,

Sorry if you’re getting sick of me posting, but I’m trying to understand what’s going on with my body.

I’ve just been to pick up one of my blood test results, taken on Tuesday, which I’ve posted. I’ve been telling my GP surgery for weeks that I don’t feel well at all, my recent private tests show very low B12, and issues with MCV and MCMH (?)

I’m not sure what these new results mean? They don’t look normal to me, but I’m very new at this...

10 Replies


My personal opinion is that if a person is symptomatic for B12 deficiency and other causes of symptoms have been excluded then they should be treated whatever the results of b12, Active B12, MMA, Homocysteine etc.

Have a close look at the detail on the flowchart from BSH Cobalamin and Folate Guidelines, especially on right side of flowcart.


My understanding is that it's saying that if second line tests eg Active B12, MMA, Homocysteine are normal but the patient responds to B12 then a continuation of treatment should be considered.


Thank you Sleepybunny

I didn’t know he was doing the active B12 test, so I’m not sure why this came up? I’m also not sure what it means?

I’m waiting for the other results...


Links about Active b12 (transcobalamin)




There is info about transcobalamin (active b12) in BSH Cobalamin and Folate Guidelines .


I think with an Active B12 result within normal range you may struggle to get GP to consider a trial of B12 injections.

Have you asked for a referral to a haematologist?

BNF suggests GPs get advice from haematologist for people with B12 deficiency symptoms where there are neuro symptoms.



If you have neuro symptoms, have you asked for a referral to a neurologist?

Perhaps GP could explain why there is a note on blood test result by serum b12 that says "okay for this patient".

I note that on your private results on other thread Active B12 was below range 22.9 (ref range 25.1 - 165) but is above range on these results.

In the 3rd link at top of this post, it mentions a ref range for Active b12 of >70 pmol/L and that results between 25 and 70 pmol/L should have an MMA test.

I'm curious at to why ref range on the Active B12 test in your photo is >30 pmol. There is quite a difference between >30 and >70 pmol. Just wondering if correct reference range has been used.

If the test was carried out at St Thomas' hospital in UK then I would expect the ref range to be >70 pmol/L

Perhaps your GP would consider ordering an MMA test.

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Thank you Sleepybunny

Loads of info there, as always 👍🏽

I have no idea why my active B12 has gone up, the only differential is the time of day the test was done, the private at 7am, the GP 11.30am

I’m struggling to understand why my GP has made notes to say this is normal, I really don’t understand! He knows my concerns, and I thought he was finally listening on Monday.

I’m still waiting on other tests results: Autoantibody screen, Coeliac Screen and Intrinsic Factor Antibodies, I’m hoping these shed some more light. Do you know how long these usually take?


the notes may not necessarily have been made by your GP - more likely they were from the lab but I'm totally confused by them and how anyone can conclude that serum B12 is 'OK for this patient'.

have you asked the GP what the comments mean and who made them ...

The serum B12 is flagged up as being abnormal (the asterisk) which makes the comment even more baffling ... and may be it doesn't really relate to the result at all but the test sample.

All I can do really is confirm that you are well and truly justified in feeling perplexed.

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Thank you Gambit62

My active B12 (private test) was 22.9 a week ago, so I really don’t understand!


Could it be that, because the holo level was "OK" HappyKatieA "low" B12 level was still OK?

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That might have been it clivealive ! I have a follow up appointment on Monday evening, I suppose I just need to wait and see.


I'm not medically trained but this might mean something to someone

"Holotranscobalamin (hTC): this marker is being examined as a more specific marker for vitamin B12 absorption capabilities. hTC is transcobalamin bound to vitamin B12 and can be a measure of the true functional serum vitamin B12 levels. hTC may be the first marker to be detected with vitamin B12 deficiency. Levels of hTC <35 picograms/L can be consistent with vitamin B12 deficiency, and may be considered, but this test is not widely available."


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Thank you clivealive O hadn’t seen that before! 👍🏽


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