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Pernicious Anaemia Society
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Could my Mum be B12 deficient?

Hi everyone,

I'd really appreciate help on how to get my mum's GP to give her B12 injections. My mother has had MS for over 40 years now. She has also been type II diabetic and taken metformin for over 10 years at least. Recently she went into hospital and was taken off metformin. The situation is complicated, however, I still think that her symptoms are neurological and she is entitled to get a proper diagnosis. So far the GP has said that her blood cells are not enlarged so she is not showing signs of low B12. My aunt, who does have 3-monthly injections in West Wales, has said that she needs to have a specialist test. Mum is in Wiltshire and tests are limited it seems. Her nerve damage is caused by MS, however, there could be a link. She has a very small appetite and unlikely to eat enough high B12 foods. Please can you advise how I arrange for my Mum to have a test and be given an injection?

4 Replies

She hasn't as the GP said that they don't do that B12 test. I am requesting to see all of her blood test results. We have just changed GP with serious concerns over Mum's treatment for her diabetes and seemingly absent monitoring of her blood sugar levels.

On what grounds should I request the test?


Metformin can interfere with uptake of B12 from diet. As you get older your stomach acidity also tends to drop which will also interfere with uptake of B12 from diet.

Testing serum B12 would be useful as well as folate. MMA and homocysteine can help to clarify if serum B12 is ambiguous - particularly MMA if her folate is low.

Would be useful to know what her iron levels are as low iron would cause a different type of anaemia from folate and b12 deficiency - smaller red blood cells - so can make interpreting full blood count very difficult.

Serum B12 isn't a gold standard test and misses 25% of those who are B12 deficient (but also catches 5% who aren't) if used as a single measure.

as Hidden says macrocytosis isn't present in 25% of people who present with B12 deficiency so lack can't be used to rule out B12 deficiency.

source of above facts is BCSH guidelines if you are writing to GP


unfortunately there is a huge overlap between symptoms of B12 deficiency and those of diabetes and MS. Generally GPS are more aware of the symptoms of diabetes than the full extent of symptoms of B12 deficiency so are likely to rule out the possibility of two conditions co-existing, which is a shame given that metformin can lead to B12 deficiency.

Metformin isn't recommended for treatment of older patients - not quite sure of the reasons but suspect that the effect on B12 deficiency is likely to be a factor.

Other notes: different protocol for treating a dietary deficiency from a deficiency caused by lack of B12 in diet. This involves lower doses orally rather than injections - so important to establish if the problem is dietary or absorption.

PA is the most common cause of B12 deficiency and will also tend to lead to problems with other minerals and vitamins because one of its effects is lowering of stomach acidity.

Test for PA - IFA is prone to false negatives 40-60% of time so a negative result is a long way from proving that PA isn't the cause.

Metformin causes problems with B12 absorption in 40% of users.


Wow this is really helpful Gambit62 and Eaoz. I want to pursue this only to see if Mum's acute condition might be alleviated with an injection. She is on Bcomplex tablets. Is it still worth a go at having the injection. Can you recommend a private practice to do the injections?


can't recommend a private practice.

what is the level of B12 in the complex she is taking?

using high levels of B12 means that testing is likely to be inconclusive - recommendation is to avoid supplementation for 3-6 months if looking for a diagnosis of an absorption problem.

High levels of B12 in serum can sometimes cause a reaction that leaves people deficient at the cell level so high level B12 supplements in the absence of a B12 absorption problem can certainly be problematic, and I wouldn't recommend injections as a test unless you are sure that your mother's B12 really is low and the cause really is an absorption problem.

Realise that you are in a position where you have low confidence in GPs but it really would be better to try and work with them if you can first - which would probably mean writing to them.

My mother is a MODY diabetic with quite advanced retinopathy, neurological problems and significant cognitive decline. she was on metformin for 40+ years (as was her father before her) even though metformin isn't really an appropriate treatment for her particular form of diabetes. Her B12 levels did start plummeting a few years ago and she had loading doses but I'm not clear what is happening about maintenances - not really clear what the effect of B12 treatment has been for her - and it didn't really seem to resolve her cognitive problems which may have been down to diabetes anyway as she has been very prone to being hyper over the years (probably because she was on metformin rather than a more appropriate medication). Her GP does seem to be supportive and did take her off metformin but it is all very complicated.


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