Thyroid UK

Advice on TFT test

Hi. Am due to have blood test following my trial period on Levothyroxine 50mcg on Wednesday. I take various supplements including biotin. I ask for your advices regarding whether I should withhold these before the blood test also Levo. My blood test is booked for 8.00 am on Wednesday as I understand it is advisable to have it early morning. Thank you friends.

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Nionyn As Biotin can interfere with tests and give false results, best to not take any more now until after the test (if you take a B Complex in addition to separate Biotin, check that and if it contains Biotin then stop B Complex as well).

Everything else, just take as normal but on the day of the test take after the blood draw. That includes Levo. There should be 24 hours between last dose of Levo and blood draw.

Fast overnight (you can have water) so don't have breakfast until after the blood draw. Eating can lower TSH and you need it as high as possible when looking for an increase in Levo or to avoid a reduction.

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