How often can i test bloods?: Hello I was just... - Thyroid UK

Thyroid UK

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How often can i test bloods?

Dolphin40 profile image
11 Replies


I was just wondering what is the shortest amount of time you can give before getting an accurate picture of thyroid results? Its for my daughter who still isn’t on the right dose. Thanks

11 Replies
Cats2018 profile image

My thyroid levels are routinely tested every 3 months. I suspect that if levels are not what they should be yet, that more frequent tests wouldn’t be out of line

Lalatoot profile image

8 weeks is what is recommended though surgeries often say 12 weeks. This is because the body needs time to adjust after a dose change.

Any sooner and you would not be testing the full effects of the change on the body.

fuchsia-pink profile image

It takes a while for things to settle down, so 6 weeks is usually seen as the shortest time.

Try and get her an early morning, fasting blood test - that will give best results

Jazzw profile image

I would say 6 weeks but whether you can get a doctor to agree is another thing—I think they’d lean more towards 8-12 weeks.

Dolphin40 profile image

They are saying 4 weeks?

Jazzw profile image
Jazzw in reply to Dolphin40

Then go with 4 weeks—is she still on quite a low dose?

Dolphin40 profile image
Dolphin40 in reply to Jazzw

Went from 25 to 50, just changed to 37.5 x

SlowDragon profile image
SlowDragonAdministrator in reply to Dolphin40

Can take longer to settle on reducing dose

So you might want to hang on a bit longer if you can

Important to retest vitamins after dose reduction

jimh111 profile image

Four weeks is recommended for getting an initial rough dose and then longer intervals when it comes to fine tuning.

I don't know your daughter's age but TSH can vary considerable during the menstrual cycle so the standard 6 weeks is the worse possible interval from that point of view. It's best to pay more attention to fT4 than TSH as fT4 is not subject to fluctuations caused by time of day and cycle. Above all pay attention to her signs and symptoms.

Dolphin40 profile image
Dolphin40 in reply to jimh111

Shes 6

jimh111 profile image
jimh111 in reply to Dolphin40

Oh! Four weeks is OK initially but once her levels are near normal I'd ask to reduce the frequency, it must be quite upsetting to have blood taken at that age. Let her school know so that they can make allowances and let you know if they notice a change in her schooling or behaviour.

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