B12 and Thyroid Test

[Libuse]

I have just ordered advanced thyroid test from medi checks and was taken aback to read that B12 should be stopped 2 weeks before test. Because of neuropathy I self inject B12 every other day and have done ever since diagnosis of hypothyroidism over a year ago, whatever blood tests I have had. Should I be desisting please before I take this, my first private test? I know about vit D and biotin but this is new to me!

[TiggerMe Ambassador]

If you already know you need these B12 injections this frequently I wouldn't stop for the sake of a blood test 🤗

[Libuse in reply to TiggerMe]

Thanks Eeyore. My feelings too X

[TiggerMe Ambassador in reply to Libuse]

Apart from stopping biotin I stick to my usual routine so it would be a 12-24 hour gap as that is my 'norm' which to me seems the most useful results 🤷‍♀️

[helvella Administrator]

It is not entirely clear if you or Medichecks are discussing testing B12 once injecting that, or for absolutely any test?

Regarding testing serum B12 once on injections, have a look here:

stichtingb12tekort.nl/engli...

But I'd ask on the Pernicious Anaemia Society forum if members have identified any reasons to stop B12 injections for any other blood tests.

[Libuse in reply to helvella]

Sorry Helvella. The test is for thyroid - TSH etc. and I wasn’t aware that B12 had any effect on results until I read statement from medichecks not to take B12 for 2 weeks before test which is why I am asking thyroid forum

[helvella Administrator in reply to Libuse]

Understood!

But I still suggest posting on PAS (as well - definitely not wrong to have posted here!). Members there will likely have come across the same sort of issue with respect to many other tests as well. And might have some useful/good information.

I might choose not to inject on the day, or the day before, but in your circumstance I'd want very solid evidence before inserting any real delays to conform to a questionable statement. Maybe ask Medichecks as well - explicitly asking for details.

[Libuse in reply to helvella]

Yes that’s a good idea to ask medichecks. I must had had 4 or 5 NHS blood test si was diagnosed hypo in Nov 22 …. Thanks for retaking the time to reply. I’d be in the dark ages without this forum

[Wua13262348 in reply to helvella]

Libuse's answer to you is a bit misleading. The test though for thyroid, includes VITAMINB12, ferritin,folate and vit d, as well as tpo antibodies, and tgab antibodies, as their advanced thyroid test includes all these. I've replied to Libuse that she just needs to tell them on her account information page that she injects B12 and that she will be high or over range for B12 because of this. They are just trying to identify people with over range B12 for no apparent reason, by asking that you stop B12 2weeks before the test. They don't mind you supplementing or injecting up to the day of the blood test as long as you tell them in your a/c info. page that this is the case. Thought I would clarify in case lots of members think it is like biotin and skews the test. It doesn't.

[Libuse in reply to Wua13262348]

Brilliant. Understood and thank you 🙏

[Wua13262348]

I had over range b12 on this test because i supplement and they told me to stop taking b12 for 2 weeks and sent another kit to do a retest. I stopped for 2 weeks for the retest and my levels reduced. Interestingly, they also stipulated that I do the test before 10a.m. I routinely do my tests at 12.10 p.m.

Next time I did the test I just told them on the a/c info page of my account that I deliberately supplement B12 high and it is likely to be high or over range as I supplement it high. They accept this. They are just trying to make sure that you don't have high or over range B12 for no good reason.

[Libuse in reply to Wua13262348]

Many thanks Wua. My thoughts were going in that direction and your response reassuring ❤️