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Pernicious Anaemia Society
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GP reluctant to give injections


I have been on regular b12 injections previously but when I moved to a different area of the country these were not continued. In the summer, feeling very tired and listless, I had a blood test in France and the b12 score was 112 so I supplemented with sub lingual b12. When I got back to the UK in November my blood test showed b12 as 304, with positive parietal antibodies but negative intrinsic factor antibodies. In spite of the fact that I do have symptoms, today my GP has said we need to wait for another blood test in March before deciding whether or not I need injections and, in the meantime, I should not take sub lingual b12 as this will skew the results. I feel really stuck as now I can't relieve the symptoms myself nor can I get him to give me injections to relieve them! It feels like March is a very long way away. Any advice ? Thanks.

6 Replies

Hi carolen do you know what your Folate level is as this and B12 help your iron to make red blood cells and to function properly in your body?

Sadly the IFA test is unreliable in that it gives false negatives in people with PA half the time. So a negative result doesn't mean that you don't have PA. However, a positive result is a sure-fire, 95% certain indicator of PA.



Yes folate level was 10 (2-18.7).

Should I supplement with Sub lingual b12 do you think and maybe leave off taking it in the run up to the March blood test ?



It has been previously recommended on this community "Taking supplements that contain B12 will affect any tests ordered by your doctor to assess your B12 status. You should not take any supplement with B12 before having your B12 assessed (including MMA/homocysteine/Active B12). For testing intrinsic factor antibodies: keep one week between an injection and the test."

I am not a medically trained person but would certainly heed Gambit62's advices below and I bid you goodnight.


Would suggest that you write to your GP pointing them towards the BCSH guidelines on diagnosis and treatment of cobalamin and folate deficiencies which they can access through the BNF but can also be accessed here


points to make

a) recommends prompt treatment where neurological symptoms are present to avoid the risk of permanent neurological damage

b) serum B12 is not a gold standard test for B12 deficiency - it will miss 25% of people who are B12 deficient if used on its own - symptoms are extremely important

c) IFA is a problematic test for pernicious anaemia - it produces false negatives 40-60% of the time depending on the test method so a negative doesn't rule out B12 deficiency.

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Your symptoms need treating , not blood test results .

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Thanks everyone, very helpful.


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