Test for hypothyroidism, does timing matter?

[Chocolatestain]

Hi, I’m due to have a blood test for possible hypothyroidism in just over a week’s time and I’ve been doing some research to try and get a bit more understanding of what might be going on and what to expect. One of the pieces of advice I’ve come across several times is to book a blood test as early as possible in the morning and fast beforehand. I assume this advice is aimed at people already taking thyroid medication, but does anyone know if it makes a difference for an initial blood test?

My test is booked for midday and I’m reluctant to change it as there is currently a three-week wait for blood tests at our GP surgery. If it gives a more accurate result, then I’ll fast beforehand, but as I’ve got work in the morning I’d rather not if I don’t have to!

Yes, I've seen that advice too - levels are supposed to be higher in the morning, at their highest at around 5am. I did a private test at 8.30am and my next one (NHS) at 2.30pm and my second results were a bit more 'normal'. You could do a private blood test with a company like Thriva just for comparison.

(I'm not on Levothyroxine because it made me feel awful so I stopped taking it. Am taking Ashwagandha and other Ayurvedic herbal remedies and am doing OK. But we're all different.)

Thank you, that’s helpful. I might try and rebook the test as it’s probably better to wait another three weeks than get an inaccurate result and have to start the whole process over again because I’m still feeling rubbish.

Thyroid UK would say as early as possible to catch the peak in the circadian rhythm, fast overnight and until the test. If you're symptomatic and looking for diagnosis, you really need to do this. Similarly if you're feeling well on meds and don't want your GP to reduce them.

I pay a mobile phlebotomist to come to my home at 8am.

Thank you. I spoke to my GP surgery yesterday and was lucky to get a receptionist who seemed to have some understanding of thyroid issues and managed to squeeze me in on Thursday morning.

The mobile phlebotomist sounds like a good idea. I’ll look into that if I’m going to need blood tests on an ongoing basis.