What is the amount of biotin likely to affect thyroid blood tests?

[Caroline888]

Hi everyone,

I had planned to do a Medichecks blood test early next week, Monday or Tuesday, but have only just remembered the advice given to stop biotin 4/5 days before the test. I take a multivitamin containing 30mcg biotin. Is this enough to adversely affect the results (TSH, FT4 and FT3)? Obviously I will not take any more of the multi before the test but will only have stopped taking it 3/4 days beforehand.

Any advice would be appreciated.

Best wishes

Caroline

[SlowDragon Administrator]

That should be fine. Biotin is water soluble, so apparently most is gone within 23-48 hours.

Obviously advice is over cautious on stopping earlier than that.

It doesn't affect every blood test, it depends what system the lab use, but as patients don't know which system is affected, we have to err on side of caution

[Caroline888 in reply to SlowDragon]

Thank you SlowDragon for your quick and helpful reply.

I always remember for the NHS tests but somehow forgot with the Medichecks test. Glad to know it should be ok. Will delay until Tuesday to be safe.

Thanks again.

Best wishes

Caroline