When on combination will Tsh be much lower late... - Thyroid UK

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When on combination will Tsh be much lower later in the day?

Clara9•

6 years ago•13 Replies

If I have my blood taken after lunch will my Tsh be much lower? Am in combination treatment and have low Tsh

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Clara9

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13 Replies

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jimh1116 years ago

There's a circadian variation in TSH which seems to originate from the hypothalamus as fT3 also varies (slightly) and follows on about 1/2 hour later. I don't know of any study that looks at circadian TSH in patients being treated with thyroid hormone. Logically we might expect the variation to continue but if TSH is already low it's not clear if it would still be affected. Maybe it is and a TSH of 0.03 at 8 am might be 0.02 at 2 pm. I'm not sure it's worth bothering about as it won't alter a doctor's opinion.

Clara9• in reply tojimh1116 years ago

That's what I was thinking. If I need to have tests done earlier than 1pm I would need to wait another week.

jimh111• in reply toClara96 years ago

I'd just go ahead. If your TSH is already low you won't notice the difference.

SeasideSusieRemembering6 years ago

Clara9

Graph of daily rhythms of TSH and FT4/FT3 are in the first post of this thread by respected Admin Helvella

healthunlocked.com/thyroidu...

On combination treatment, the T3 will lower TSH, maybe even suppress it.

If you are looking to get your TSH as high as possible, an appointment around lunchtime wont help, nor will eating as it's said that eating can lower TSH. Usual advice on the forum is blood draw as early as possible, no later than 9am, delay breakfast until after the blood draw and water only as coffee can also affect TSH.

jimh111• in reply toSeasideSusie6 years ago

Eating a moderate meal has no effect on TSH.

SeasideSusieRemembering• in reply tojimh1116 years ago

jimh111

I'm not having this conversation with you again.

See Diogenes replies to mandyjane and humanbean in this thread healthunlocked.com/thyroidu...

diogenes

•in reply to mandyjane

4 months ago

Actually, with long duration exercise FT4 and FT3 levels actually fall somewhat. With meals, TSH is most affected.

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diogenes

•in reply to humanbean

4 months ago

TSH falls after eating, but FT4 not affected. Don't know about FT3 but suspect it will behave like FT4.

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I've suggested before you discuss it with Diogenes if you're questioning what he says.

jimh111• in reply toSeasideSusie6 years ago

You've said this before. I am not going to drag a third party into this, it's damn rude. If you have ANY evidence whatsoever then give me the references to the studies and I will read them. (There was one study that suggested this, a couple of years later the authors recognised their mistake and put the record straight in a follow up study.)

We should give advice based on facts rather than just repeating gossip senseaboutscience.org/ .

By wrongly stating we need to fast before a thyroid blood test you are putting out a statement that should be corrected. It would be better if both of us didn't mention food and blood tests and thus not have this distraction.

Taking L-T3 has no more effect on lowering TSH than an equivalent dose of L-T4. This was demonstrated by an excellent prospective, randomised, double blind, cross-over study by Francesco Celi who is one of the world's best thyroid researchers ncbi.nlm.nih.gov/pmc/articl... . TSH is just as valid for liothyronine therapy as it is for levothyroxine, i.e. sometimes useful sometimes not, depending on clinical response and other factors.

SeasideSusieRemembering• in reply tojimh1116 years ago

JImh111

If you don't like what I say, don't address your responses to me.

I am not going to drag a third party into this, it's damn rude.

If it's Diogenes who made the statement in the first place, as shown in my response above, he's not exactly a third party. If you don't agree with his statement then your disagreement is with him not me and who better to give you evidence than a scientist who has been involved with clinical trials and written papers on thyroid function.

We should give advice based on facts rather than just repeating gossip

So what Diogenes say is gossip then? I'm sure he'll be happy to know you consider his statement to be that.

By wrongly stating we need to fast before a thyroid blood test you are putting out a statement that should be corrected

Not only does Diogenes say that eating affects TSH, this has been advised by another Admin's endocrinologist. And I would remind you that out of all the members and Admin who respond to posts you are the only one who who says this, there are many who suggest fasting or delaying food until after the blood draw. But it seems you like to only pick on me, I can't recall you challenging anyone else, but please point me in the direction of where you have.

Same goes for T3 lowering TSH.

It would be better if both of us didn't mention food and blood tests and thus not have this distraction.

Do what you want, but don't tell me what to do. If you find it a distration then ignore my posts and don't respond directly to them.

jimh111• in reply toSeasideSusie6 years ago

I don't mean to pick on you, I'm sure I've given similar responses to other members who have claimed eating affects TSH as well as members on the TPA forum. It's a shame someone didn't pick up on this a long time ago since once a belief gets ingrained and passed on it's difficult to change minds. As an example you put this link in your earlier post healthunlocked.com/thyroidu... . All the patients in this trial had lunch and dinner at the same time but there is no variation in the graph following these meals. You supply an excellent example of food having no effect on TSH.

T3 lowers TSH just like T4 does but it's 3x as potent in doing so. If you take a lot of T3 or T4 it will suppress TSH.

Clara9• in reply toSeasideSusie6 years ago

What would you do? Wait a week and have it done early morning or go ahead in the pm? Latest Tsh was 0.01

SeasideSusieRemembering• in reply toClara96 years ago

Clara9

It depends on whether your doctor is going to take notice of the TSH or the FT4/FT3 results.

Is your T3 prescribed? If so then the prescribing doctor should know that taking T3 will lower, often suppress TSH, so it is irrelevant.

When taking T3 the only result that is important is FT3, if that is in range you're not overmedicated.

If the TSH result is important to your doctor then do the test as early as possible and delay breakfast until after the blood draw, drinking water only.

Also leave off Levo for 24 hours and T3 for 12 hours so that you get the normal circulating level of T4 and T3. If you take them closer to your blood draw you will get a false high result, and if you take them any longer than those times you'll get a false low result.

Clara9• in reply toSeasideSusie6 years ago

Thank you ever so much for your advice. 😊

Angel_of_the_North6 years ago

TSH is always lower later in the day, and will generally be lower when you are taking T3. I wouldn't have an afternoon test, but cancel and reschedule for the morning, when you can take your test fasting as well. TSH isn't really important, it's free t3 that you need to take notice of, but GPs tend to be TSH obsessed.

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