Breakfast or not?

[Quester]

Hello helpful folks! I’m going for another blood test this week. I think I saw someone saying you should not eat before this and not take your Levo? The test is at 9.10 am so I can probably manage this.

(Doesn’t help that I’m blood phobic though!)

[SeasideSusie Remembering]

When booking thyroid tests, we advise:

* Book the first appointment of the morning. This is because TSH is highest early morning and lowers throughout the day. If we are looking for a diagnosis of hypothyroidism, or looking for an increase in dose or to avoid a reduction then we need TSH to be as high as possible.

* Fast overnight - have your evening meal/supper as normal the night before but delay breakfast on the day of the test and drink water only until after the blood draw. Eating may lower TSH, caffeine containing drinks affect TSH.

* Leave off Levo for 24 hours before blood draw, if taking NDT or T3 then leave that off for 8-12 hours. Take after the blood draw. Taking your dose too close to the blood draw will give false high results, leaving any longer gap will give false low results.

These are patient to patient tips which we don't discuss with doctors or phlebotomists.

[Quester in reply to SeasideSusie]

Thanks a lot Susie 😊

[SeasideSusie Remembering in reply to Quester]

You're welcome

[manxonia]

I was told it makes no difference,just do what u do every day!!

[humanbean in reply to manxonia]

Who told you this?

[manxonia in reply to humanbean]

The nurse that took my blood,also a pharmasist.

[humanbean in reply to manxonia]

Diagnosis and dose of Levo depend on the result from the blood test.

If the blood is taken soon after you take a dose of Levo your Free T4 might be very high.

TSH is determined by time of day, so getting blood taken at the wrong time could mean you get a very low TSH result. This might mean that dose of Levo gets reduced.

See the graphs on this post :

healthunlocked.com/thyroidu...

TSH is lowered by eating, apparently, so I would fast if I had a blood test for thyroid.

Please note that nurses and pharmacists don't have their quality of life determined by a thyroid function test. People with thyroid disease do. If Free T4 is high doctors may reduce dose of Levo. If TSH is low doctors may reduce dose of Levo. Most patients want to reduce the possibility of this happening. Ignoring the advice of other patients is bizarre.

To see the paper that the graphs are based on, go to this link :

academic.oup.com/jcem/artic...

then click on "PDF" for the full paper.

[Quester]

Thank you 😊

[Hidden in reply to Quester]

There is conflicting advice about T3 here. That it should be taken within a certain period, but at present I'm not sure.

[SeasideSusie Remembering in reply to Hidden]

It's 8-12 hours between last dose of T3 and blood draw, but Quester hasn't asked about that, they're on Levo.

[Hidden in reply to SeasideSusie]

Yes, that's right. It was referring to the response that mentioned T3 and really only in case someone came across it another time.