Is there a best time of day to do blood tests? - Thyroid UK

Thyroid UK

113,298 members131,618 posts

Is there a best time of day to do blood tests?


I have jusy ordered thyroid blood tests from blue horizon to do at home. Just wondering if there is a best time of day to do them. I know this may sound awful but I want tests to be at their worst so to speak as my gp is refusing to re run tsh and ft4 I had done 15 months ago and said there was no point as they wouldn't have changed in this time. Would be grateful for some help on this

10 Replies

early morning.. x

If you are on thyroid meds, don't take it until after your test..



Thanks. I m not on any medication

shawsAdministrator in reply to Alex97

Have your test as early as possible as that's when the TSH is highest. I am not sure about the others. You could phone Blue Horizon just to double check with them.

I've recently done this. My NHS bloods at the beginning of Feb at 9.00am were TSH 3.8 (0.27-4.2). Did my BH test at 3.45am and my TSH went to 7.08 (0.27-4.2). Just have a 3 week wait to see my GP now.

Good luck with the test, it's easier than it sounds :)

Alex97 in reply to lunamoona

Thanks for reply. So your tsh was higher in the afternoon? gp doesn t think it would alter in 15 months. Last tests feb 2013 tsh 1.5 (0.28-5) and ft4 13.5 (12-19).

lunamoona in reply to Alex97

No, BH test was done at 3.45am (in the morning). Bit of a drag but worth it.

Alex97 in reply to lunamoona

Ah! Sorry, didn't read it properly. I will give this a try. I m usually awake anyway

Draw blood as early as possible in the day.

Did mine at 5am - nearly 2 points above - went from 3.14 (blood taken at 4.50PM) to 5.07 taken at 5AM - well worth the effort. Nobody teaches Docs about Body Clocks!!! XX Good Luck - if you can't get the blood out, stand up.

Yes - as everyone says, get them done as early as poss. I have a conundrum:

I'll soon be having two TSH tests, one ordered by endo and the other ordered by GP and each going to a different lab.

What's the possibility of getting a private phlebotomist drawing bloods as early as poss (well before the hospital phlebotomy depts are open) in response to NHS request? Not sure it's viable but I could ask. I'd be interested to see the difference between the two readings from the different labs.

You may also like...