How much does Vitamin B affect test results?

[PandoraXX]

I retested my T3, T4 and TSH after 6 weeks since my last test. I hadn't changed the dose of my T3 or T4 medications but just wanted to check things. The results were virtually the same as before. Then afterwards I realized that I'd forgotten to stop taking my Vitamin B suppliments. So my question is - does Vitamin B always interfere with test results? If so, how much and which results in particular?

[Lalatoot]

Vitamin B does not affect results. Biotin affects results. Biotin is contained in vitamin B complex supplements. Biotin is not in vit b alone. You would need to check your supplement to see.

[SeasideSusie Remembering]

Does your supplement contain biotin (B7)? It's the biotin that can cause false results when the lab uses biotin in the testing equipment. So if your supplement does contain biotin then you'd need to know if the lab uses it when testing. If so the results may be false but it's not really clear how it affects them.

The higher the dose of biotin the longer it should be left off. The amount in a B Complex is often around 400mcg, so if it's that low it may not make much difference as long as you didn't take it before your test on the day .

[PandoraXX in reply to SeasideSusie]

Thanks for the responses! I should have been clear, I am taking VB Complex along with B12 - so perhaps as Seaside Susie said, it's too low to affect things. But I did take it the day before. I guess I'll just re-test in a few weeks and make sure I stop taking it.

[waveylines in reply to PandoraXX]

It cann affect with biotin. I had a blood test & wasn't told it they were checking my thyroid levels. I had taken my thyroid meds and not stopped my B complex for a week.My results were massively over range for my ft4 & Ft3. So it was retested a week later before my thyroid meds & I stopped the B complex for a week. Ft4 & Ft3 were both mid range. Actually needed an increase.