8 or 10 weeks blood test ? to check l... - Pernicious Anaemi...

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8 or 10 weeks blood test ? to check levels


Hi. I am finding 10 weeks too long to wait for my b12 injection - by 10 weeks i am already getting bouts of exhaustion, clumsiness and dippiness.... My doctor isnt keen on earlier doses, as he has already brought it forward from 12 weeks at my request.

He has suggested a blood test to check my levels . Would anyone be able to suggest if I should have the blood test at my normal.10 week point, or should I do it at the 8 week point? I am hoping he will let me have 8 weekly injections so I don't get to the fatigued stage. Thank you if anyone can advise. And beat wishes to all

5 Replies


beginner1 in reply to luckymaria

A blood test is pretty useless after you have started injections. (And when it comes back high, which is usual, some GP's use it as an excuse for stopping injections) The NHS guidelines are - no testing after treatment.

If you have neuro. symptoms (according to the guidelines) you should be getting injections every 8 weeks (every 2 months)

Good luck with getting that - some GP's haven't read the guidelines.

luckymaria in reply to beginner1

Ok. Thanks for that. Fingers crossed.


To be honest serum B12 (and active B12) are unlikely to be useful tests at this point. Possible that they may come back low which would mean that you remove the B12 quickly from your system and need B12 more frequently but the likelihood is that your levels will be well into the normal range if not over at 8 week but that doesn't mean you are okay as the test doesn't tell you what is happening in your cells.

Raising B12 levels kicks off a reaction in a significant number of people, that basically stops B12 passing from blood to cells, and can also stop it being recognised as excess B12 and removed by the kidneys. In general if this is going on then MMA and homocysteine levels would be raised but some experts don't think this is always the case. They are also expensive tests.

Ideally frequency should be determined by when your symptoms return but it's difficult to find a GP that understands or will treat on that basis.

luckymaria in reply to Gambit62

Ok thank you for your help. 😁

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