Thyroid blood tests.

[Gardeningbuff]

Do you need to fast for thyroid blood tests?

[SeasideSusie Remembering]

General advice here for thyroid tests is always do them under the same conditions every time so they can be compared accurately. We usually say

* Earliest appointment of the morning for blood draw. This is because TSH is highest at midnight and lowers throughout the day, lowest being around 1pm. If looking for a diagnosis, an increase in Levo or to avoid a reduction then the highest possible TSH is needed.

* Fast overnight - have evening meal/supper the night before and then water only until after the blood draw. This is because eating can lower TSH, coffee also affects TSH, so again if TSH result is important and you want it as high as possible then fast as described.

* Leave off Levo for 24 hours before blood draw. This is because taking Levo too close to blood draw gives a false high FT4 and taking it more than 24 hours away from blood draw gives a false low FT4.

[Gardeningbuff in reply to SeasideSusie]

Hi SeasideSusie. Im looking for a diagnosis. General advice you dont need to fast, but someone mentioned its best if you do in her opinion. I want a diagnosis so much. I have really unpleasant pins needles tingling always freezing, and I'm in a warm climate, fatigue, little appetite. I've had these symptoms for about 2 years. My iron was very low( had bowel surgery) so had an infusion and b 12 injections. They seem to be normal now. Seeing gp on Friday.

[Hidden in reply to Gardeningbuff]

You have asked what to do and seaside susie has replied with exactly the correct information if you want to do your own thing, why did you ask? Ofcourse you should fast this is correct.

[Gardeningbuff in reply to Hidden]

Did i say i want to do my own thing? If i did i didn't mean to. I am taking advice from experts on forum and fasting, as advised. I am new to this. Maybe it wasn't meant to be criticism, but it sounded like it. I need support.

[Hidden in reply to Hidden]

Sorry if I was rude it's just that so many ask for advice and simply don't follow it.

I know that it works on this site because I have followed the advice and am now well. Hopefully you will be soon too. By the way I do my own thing I never visit the GP's or Endos just post my results on here for answers

I am lucky apart from no gallbladder or Thyroid I have no other problems.

[Gardeningbuff in reply to Hidden]

Thank you Bunnyjean. I will follow any advice. I so desperately want to feel good again. I've had a dreadful year I was probably just being too sensitive. I must admit I don't blame you regarding gp's although I think I have found a good one, and my colorectal surgeon was wonderful, he had such a mess to sort out inside my little body lol. I was lucky to find him. Best wishes.

[Hidden in reply to Gardeningbuff]

Good you are lucky when I lived in Southampton I had a good one but I have moved now so back to the drawing board.

[SeasideSusie Remembering in reply to Gardeningbuff]

Gardeningbuff

OK, so you need your TSH to be as high as possible. So have your evening meal the day before (please do eat normally the day before, some people have fasted for 24 hours which is totally unnecessary) then book the earliest possible appointment at the doctors for your blood draw and have water only, delay breakfast/coffee/etc until after the test.

Ask for a print out of your results and post them on the forum (include the reference ranges) and members will comment. If you can get any of your basic vitamins and minerals done too, that will help complete the picture - Vit D, B12, folate and ferritin.

[Gardeningbuff in reply to SeasideSusie]

Will do. Ive got the 1st appointment of the day. Will they ask if i have fasted? They don't always.

[SeasideSusie Remembering in reply to Gardeningbuff]

My surgery has never asked if I fast in over 40 years. Just don't bring the subject up. If they do ask, it's up to you whether you tell them or not, just be prepared for them to say you don't need to, but they really don't know much at all.

It's surprising how many tests require fasting but they don't tell you. I recently found out about this for iron tests which I've never been informed of:

•Blood samples should be taken early in the morning for the iron level test, since iron levels vary throughout the day.

•While no fasting is required before a ferritin test, recent ingestion of a meal containing a high iron content (from red meat, for example) can cause elevated levels.

•Do not eat or drink anything for 8 hours before a blood test for iron level, TIBC, or transferrin. No fasting is necessary before a test for ferritin levels.

•Do not take iron pills for 24 hours before the test (although I've also seen it said leave off iron for 7 days)

[Gardeningbuff in reply to SeasideSusie]

I've had bad experiences with blood tests. I had a massive diverticular infection this time last year. Silly gastro doc released me from.hospital and i had a massive abcess in my bowel. He said blood tests were fine so i couldn't have. Long story short i kept telling him i was still feeling extremely unwell. Ended up being sent to surgeon, who had to repair damage abcess had done. Two major ops and a bag for 3 months. Horrible year.

[Angel_of_the_North]

You also need to be sure not to take any supplements that contain biotin (eg B vitamins, multivitamins) for a few days before the test.

[Gardeningbuff in reply to Angel_of_the_North]

Thank you Angel_of_the_North . Good advice. I will do that. 😊

[Raventhorpe]

Hi Gardeningbuff good advice from all the others so just wanted to wish you good luck with getting diagnosed.

[Gardeningbuff in reply to Raventhorpe]

Thank you Raventhorpe. Fingers crossed! 😊

[Gardeningbuff]

Thanks everyone for your help today