Pernicious Anaemia Society

Advice on b12 levels post loading doses

Hi i am after some advice please. I had 6 b12 loading doses in October 2016. I was deficient in b12 and folate after bloods tests. My GP requested PA serology but the labs made a mistake and did my b12 level it came back 1500 in November. We did expect that. It took 4 attempts and a complaint to the bloods dept before they finally did the test which came back negative. My gp said i would only get 3 monthly jabs if i have PA. This week she checked my b12 levels again and they have dropped to 375. Is it normal for the level to drop so quick. I have booked a double appt with her because all the symptoms are coming back. I feel i should be on 3 monthly jabs and want to fight my corner with this. Any advice would be appreciated.

2 Replies

The guidelines provide for treatments in two cases - problems caused by lack of B12 in your diet - which can be treated by tablets - and treatment by injections if the cause isn't dietary (PA being just one possible non-dietary cause). However the NICE guidelines are not well written and it is easy to understand them as saying that injections are only necessary if the cause of deficiency is PA - but this is not correct.

Additionally, the test for PA is prone to false negatives - about 50% of the time - so a positive result would have demonstrated that you do have PA but a negative is not conclusive evidence that you don't have PA.

Other absorption problems include: drug interactions - including PPIs and metformin used to treat type 2 diabetes, lowering of stomach acidity as you get older, general absorption problems such as Crohns and Celiacs.

Problems caused by h.pylori infections can be treated and reversed, as can tapeworm (occasionally crops up in scandinavia) so injections would not need to continue after those conditions have been treated for.

Most people store B12 in the liver and then release it into the ileum as needed but if you have an absorption problem in the ileum then this doesn't work and the B12 just leaks away through the gut. B12 you have from shots can stick around in your blood for a while - how long varies significantly from one person to another. After you have had shots then levels don't really mean anything unless they come back low - as they did in your case - which means that your kidneys are quite efficient at removing B12 from your blood and you need shots at regular intervals.

Basically your GP is, like many others, not very familiar with B12 deficiency, how it works and how it needs to be treated.

Suggest that you point your GP at this part of the PAS website as an opportunity to learn more about the condition and ensure that she is treating her patients appropriately.



Hi faras66 you wrote "My gp said i would only get 3 monthly jabs if i have PA. " but according to the BNF Guidelines:

"Standard initial therapy for patients without neurological involvement is 1000 μg intramuscularly (i.m.) three times a week for two weeks, then every three months.

The BNF advises that for Pernicious anaemia and other macrocytic anaemias patients presenting with neurological symptoms should receive 1000 μg i.m. on alternative days until there is no further improvement, then 1 mg every 2 months.

However, the GWG recommends a pragmatic approach in patients with neurological symptoms by reviewing the need for continuation of alternative day therapy after three weeks of treatment "

You say that you were "deficient in b12 and folate after bloods tests" Did your doctor prescribe or have you been supplementing with folic acid?

I hope this helps and wish you well.


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