Pernicious Anaemia Society
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Do they test for B12 when you have a thyroid function test?

I recently had 6 loading injections of B12, my next injection is due in 3 months.

In a few weeks’ time, I’m due to have a thyroid function test. I’m a bit nervous about having the thyroid test, as I’m not sure if they also test you for B12 at the same time? Obviously I’m expecting my B12 levels to be nice and high, due to all the recent injections, and I’m scared that if any doctor (other than my usual GP, who arranged the B12 injections) sees the results, they may think “blimey, this patient has very high B12, let’s take her off injections”.

I may ring the surgery, speak to my usual GP, just to see if (a) B12 gets tested during a thyroid function test; and (b) if I can arrange for the results to go straight back to her, as she knows the history. But I just wondered if anyone here could help, to save me ringing the surgery?

I’m feeling fine at the moment, so I suspect my thyroid levels are OK, in which case I may decide not to have a blood test and avoid potentially rocking the boat ……

I’m posting this in both the Thyroid and the B12 areas of Health Unlocked, I hope that’s OK.

3 Replies

Generally speaking B12 isn't a test that is done routinely but has to be specifically requested so I would be surprised if it was done as part of a thyroid review.

As for possibilities of misinterpreting test results - you can't do anything by worrying about it and it is quite possible that it isn't going happen. There are options if it does so just leave it for now and come back if it becomes an actual.

there are no problems with posting stuff on two fora - not everyone is a member of all fora - I'm not a member of the thyroid forum and I'm sure there are lots on the thyroid forum who aren't members of this forum


I don't think they would usually, in your case they might as you're having the injections, so it's worth checking. My surgery wanted to retest my B12 after treatment but I explained there was no need (I had the same idea as you!) so they didn't.

1 like

Hi, I just had bloods for thyroid taken yesterday and am in discussions with doctor re having therapeutic b12 injections. I mentioned about retesting and monitoring once b12 injections received and she said NHS don't ordinarily do it as the levels are expected to be high anyway. On an aside to that, my discussin with Martyn Hooper, PAS chairman last week was that doctors should no longer use the test results for b12 as they are no longer an acceptable measure. There are new guidelines which are failing to reach our GP's which recommend treating the symptoms rather than go by the restrictive, misleading range. My concern would be that once the symptoms disappeared they would cease to medicate. You read horror stories regarding refusal of the frequency of injections being altered to alleviate it that b12 is a vitamin and cannot be patented? It can't be generating income for the big pharmaceutical companies if that is the case unless they find a synthetic alternative and market it as some miracle cure!! Call me cynical.. 😕

Would really be interested in the outcome of your quest as I am in the same situation. Take care Jax 💕


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