B12: Hi, just looking for some advice on b12. I... - Thyroid UK

Thyroid UK

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Hi, just looking for some advice on b12. I was told by blue horizon my levels of b12 were low at 270, so I saw my GP who didnt seem to concerned, but said I could buy some over t he counter supplements if I wished. I bought Jarrow 1000 b12 off amazon. When I next saw my GP three months later after a blood test it had gone up to 750. Trouble is the new GP said they couldnt test for P.A now as the results would be scewed. Surely they should have done the tests before they told me to take the supplements. So now I am wondering how long I need to be off the supplements before they can do the test and if coming off will do any damage. Any help appreciated.

4 Replies

Your reasonably good B12 result you have recently had is due to your supplementation - so not a true result. Also only 20% of the 750 will reach the cells where it is needed. The test for PA is testing the anti-bodies - for Intrinsic Factor and the parietal Cell AB. So I am afraid your GP is incorrect in saying the B12 you are taking will skew the result. It will not affect the anti-bodies if you have them. Just be aware you can have a negative result and still have PA.

There are other tests that should be done like Homocysteine and MMA which is a urine test to confirm the B12 deficiency. Due you have low stomach acid ? You need good acid for the B12 to begin it's journey from food to absorption. Homocysteine is often raised when B12 is low.


So much information in the above link - but you will need to do lots of reading. Hope it's helpful.

granny22 in reply to Marz

Thank you for your help, I will read the link.

Ann22, PA Society forum will probably be able to advise whether supplementing B12 is likely to skew tests for pernicious anaemia and whether you need to stop supplementing. I do know that you need to stop supplementing for 4 months if you want a baseline B12 result.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

granny22 in reply to Clutter

Thanks clutter, I will have a look on the P A site.

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