Medichecks advice about B12 and Biotin

[Pearlteapot]

Edit! I see that I myself asked this same question a few months ago! Going mad or I claim brain fog! heh. Sorry.

healthunlocked.com/thyroidu...

Medichecks have told me to stop Biotin 2 days before a test and B12 two weeks before a test. I don't think I have seen this warning before. I knew about the effect of Biotin which can distort the assays for T3 and T4 upwards but i have never heard of stopping B12 for two weeks prior.

What is the effect of B12 on the tests?

And does Biotin raise or lower TSH? I assume that it lowers it but the article I read only referred to the effect on T3 and T4.

This post from 5 years ago says the Biotin can result in both false lows and false highs of T3 and T4 but again, the idea of stopping B12 seems to be because B12 complex contains Biotin. But the advice I received from Medichecks today treats the B12 separately from Biotin and with a much longer period of desist.

healthunlocked.com/thyroidu...

[Charlie-Farley]

Woo Hoo!

I just called them up Pearl and its not really clear on the webpage but the lass I spoke to said she thinks, its to do with being prescribed B12 by the doctor. So if that's B12 injections, I'm guessing that, a loading dose could have longer effects than daily oral supplementation. I've not heard of anyone getting over the counter B12 pills prescribed.

Still not 100% bottomed out on that, but most likely I would think. Hopefully others may know more?

[Pearlteapot in reply to Charlie-Farley]

The replies that I had last time I asked this question were that if you want to test your non-supplemented level of B12 then you should stop taking B12 at least two weeks prior to test (probably much longer) but if you want to know what your levels are with supplementation then there is no need to stop.

So glad to be able to answer my own question! duh.

Biotin, we know, affects the accuracy of the thyroid tests.