biotin and thyroid blood text

[1965Katy]

Hi all,

Just a quick question, how long do I need to stop taking biotin (B Complex tablets) before blood test for TSH, FT4 and hopefully FT3?

I have a test booked for Wednesday 8.30 am and stupidly forgot to stop taking my B Complex. Is five days enough or should I delay blood test for a couple of days to make it seven clear days of no biotin? Blood test appointments are easy to book.

Thank you for your help.

[Star13]

Yes if you stop today it should be fine.

[1965Katy in reply to Star13]

Thank you

[Sleepman]

Helvella blog say

This paper reports that the effects of up to 300 micrograms a day are unlikely to have any clinical relevance. And leaving off the supplement for two days should be sufficient on that dose.

The clinical significance of low dose biotin supplements (<300μg/day) in the treatment of patients with hypothyroidism: crucial or overestimated?

[1965Katy in reply to Sleepman]

Thank you.

My B Complex bottle says it contains 30ug and 60% NRV. I'm not sure how many micrograms that is?

[tattybogle in reply to 1965Katy]

ug is just another way of writing mcg . no idea why they do that , but it's 30mcg

[helvella in reply to tattybogle]

mcg = µg = ug = microgram

Try typing µ on a standard UK keyboard! Or printing µ on the sort of printer we used to have - daisy wheel or whatever! We have the luxury of laser, etc., these days.

helvella's Vade Mecum document is available here:

helvella - Vade Mecum for Thyroid

The term vade mecum means:

1. A referential book such as a handbook or manual.

2. A useful object, constantly carried on one’s person.

helvella.blogspot.com/p/hel...

Screenshot of vade mecum

[1965Katy in reply to tattybogle]

thank you

[helvella in reply to Sleepman]

helvella - Biotin supplementation and testing

A short article about how and why biotin can affect blood tests. Includes information about how to avoid any problems and how much biotin some foods contain.

Last updated 03/01/2025.

helvella.blogspot.com/p/hel...

[1965Katy in reply to helvella]

That's very helpful, thank you.

The food list was interesting too 😀