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Thyroid UK
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Do people stop levothyroxine before testing?

I have a friend who has hashimotos and has been on T4. However, she is loosing hair really really bad and has so little hair left. GP won't do any other test than TSH and T4 and keeps telling her there are no other thyroid medication other than levothyroxine!

She is going to do the total tyroid screen test from Genova Diagnostic to see what her levels are. She is then going to try and see Dr Peatfield with the results. Should she stop her thyroxine prior to testing at all?? I am on T3 and I usually stop taking 24 hours before testing if I am seeing my endo but am just not sure if this is the case with T4 or not??

thanks all

7 Replies

Yes it is. Even Dr Weetman has gone on record saying you should stop levo before testing.

If you take it in the morning, do not take on the day of your test, get tested as early as possible, and then take your levo.

If you take it at night, do not take it the night before the test and also the night before that.

It has a long half life, so you will be fine.


I would not say to skip two bed-time doses.

I take my levothyroxine at bed-time and defer that dose until after the blood draw on the next day.


1 like

She takes hers around 8am and the blood is going to be drawn around 8am so I suggested that she takes it after the blood is drawn. Does that sound reasonable?


Very close to what I do - every time.


This what is available in the UK. Maybe her GP will try a lactose free levo, or liquid levo (more expensive I believe). Ask the GP for a trial. I was more unwell on levo than before diagnosis.


Hair loss can be linked to low ferritin. Its been proven in a double blind study.... To keep hair the ferritin needs to be at approx 70. The lower the ferritin,the more the hair loss..... Has she had hers tested? It seems to often run low in hypothyroidism.


Thanks galathea. She told me her GP told her it was borderline and she does not need to worry about!! I told her to get hold of her test results...


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