Active B12 test advice: Hello all... - Pernicious Anaemi...

Pernicious Anaemia Society

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Active B12 test advice


Hello all. Wondering how long you should wait to get an Active B12 blood test. My daughter is still very unwell with neurological symptoms. Neurologist did MRI and it came back normal. She thinks my daughter has Chronic Fatigue and Functional Neurological Disorder. She noted that she walked in a 'strange manner', and wrote in a report that she could walk! Gastroenterologist said to continue with 3 monthly injections and to get a referral to see a Endocrinologist as her Alkaline phosphatase won't settle down. Sent twice to A and E with tachycardia, consultant says tests are normal, but no advice if any meds are needed for tachycardia. G.P still saying that B12 would not cause any symptoms like this. She looked at the last B12 results in May which were at 1426,ng/L and said her levels are too high and she should have injections every six months, even though Gastro said 3 monthly. We are totally muddled up and don't know what to do. Daughter feels extremely dizzy and balance is bad again. She had her last B12 injection in March, is it a good time to get the Active B12 test done now? I was going to get the Blue Horizon tests for everything including the full thyroid as my faith in the medical profession being thorough has deminished. Any advice out there would be appreciated as my daughter deserves her life back. Thank you.

2 Replies


"Gastroenterologist said to continue with 3 monthly injections"

G.P ....looked at the last B12 results in May which were at 1426,ng/L and said her levels are too high and she should have injections every six months"

I don't know why she is not on 2 monthly injections as she has neuro symptoms.

See following links for more info on UK B12 treatment.

UK B12 documents

BSH Cobalamin and Folate Guidelines

Flowchart from BSH Cobalamin and Folate Guidelines

BMJ B12 article



Might be worth joining and talking to PAS (Pernicious Anaemia Society), who may be able to point you to useful info.

PAS (Pernicious Anaemia Society)

Based in Wales, UK.


PAS tel no +44 (0)1656 769717 answerphone

GP appears to be concerned about high B12 after B12 injections. Some on forum have B12 levels well into 1000s ng/L. Might be worth showing GP following documents/articles

Treatment with high dose vitamin B12 been shown to be safe for more than 50 years

Misconceptions about a B12 deficiency

More info in summary of B12 documents in third pinned post on this forum.

Active B12 test

I am not medically trained.


not worth doing active B12 test at all in the current circumstances. It is a test for whether B12 is being absorbed from food which isn't the issue here.

Tests that might be appropriate are MMA and homocysteine which will come back high if her cells are not getting enough B12, showing that she does need more frequent injections.

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