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Pernicious Anaemia Society
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Which tests can be done to see if there is an absorption problem, without having to stop supplementing?

I've been taking sublingual for months now. I would like to know WHY I'm always low in range (between 150 and 200) without supplementing, but would prefer to keep supplementing instead of quitting for months.

Are MMA/Homocysteine/Active B12 tests reliable while supplementing?

3 Replies


My understanding (I'm not medically trained) is that MMA/Homocysteine/Active B12 (transcobalamin) test results can be affected by prior supplementation.



Link about What to Do Next if B12 deficiency is suspected


Do you have recent results for folate, ferritin and full blood count tests? My understanding is that iron, B12 and folate metabolism is interlinked so l think good levels of each are needed.

Risk factors for PA and B12 Deficiency




Have you had an Intrinsic Factor Antibody test? IFA test can help to diagnose PA but it's still possible to have PA even if IFA test result is negative or normal range.

Coeliac Disease

Can lead to B12 deficiency due to effect on gut.

NICE guidelines Coeliac Disease (2015 version)


In UK, two first line tests are recommended for Coeliac disease.

1) tTG IgA

2) Total IgA

Have you had both tests? My experience is that the Total IgA test is not always done. I think it's important because people with IgA deficiency will need different tests for Coeliac disease.


B12 books I found useful

"What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Martyn Hooper is the chair of PAS (Pernicious Anaemia Society) based in Wales, UK.

"Living With Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Has several case studies.

" Could It Be B12?: An Epidemic of Misdiagnoses " by Sally Pacholok and JJ. Stuart (USA authors)

Very comprehensive with lots of case studies.


If you're getting B12 into your body, and into the cells, with your sublinguals then MMA, hCys and Active B12 should all show normal values.

If taking the sublinguals kept my levels high and stopped my symptoms then I'd be quite happy with that.


Unfortunately the MMA and homocysteine tests would require you to stop supplementing for at least three months. I have stopped all supplements of B12 at the moment for a second MMA test. I'm now wondering whether it is the best thing, as I feel awful. To be honest, I didn't think that the extra B12 was working as the tiredness didn't really go away, but other symptoms are returning. Now I have a sore tongue again and pins and needles seem to be worse, I have a feeling that I will deteriorate more as time goes on. Not sure it's actually worth it!


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