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Thyroid UK
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Blood Test on T3 only?

After my own private tests showed my NHS prescribed Levothyroxine didn’t work (zero conversion), my GP gave his blessing to be doing my own thing & offered blood tests.

Been on 50mcg T3 only for several months now & want to run a test to see how I’m doing.

Do I take my T3 on the morning of the blood draw or not?

What should I expect? Guessing my TSH should be suppressed, T3 good, but T4 nonexistent?

I’ll do my own private tests before doing an NHS one. If I can achieve optimum levels on T3, maybe I can pursuede my GP to prescribe me T3.

Thanks

14 Replies
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I take 60mcgs of Liothyronine a day for the same reason. I don’t take my tablet on the morning of a blood draw. My TSH is usually around 0.02, T4 non existent and T3 in the upper quadrant of the range. Hope this helps.

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Thanks!

Were you recommended not the take the T3 on morning of blood draw? Is that the norm?

I just wonder if that’s the most accurate measure, given the short half-life.

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We don't take any thyroid hormones, levo, T3/T4 or T3 only before blood tests and also fast as results would be seriously skewed and doctors reduce or adjust your dose.

They get worried in case we get a heart attack etc.

Professionals seem to have been told that a very low TSH causes heart attacks but someone whose had thyroid cancer have to have a suppressed TSH and TSH is from the pituitary gland.

T3 is absorbed into our system in a few hours but the effect of that one dose lasts between one to three days.

I hope you find the benefit of taking T3. The following expert only took an initial blood test for diagnosis and thereafter it was all about the relief of clinical symptoms.

web.archive.org/web/2010103...

I take T3 only and get a yearly blood test.

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Thanks!

I certainly feel OK on T3. Nothing huge, but certainly better than Levo or NDT. On both those I always felt slightly poisoned & had some side effects.

In the early days I experimented with T3 dose & went to huge levels without any ill effect, but no real benefit either.

I’m lucky to be above average fitness.

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We usually don't need huge levels of T3 only those who have thyroid hormone resistance have to have higher doses to relieve their symptoms. I don't split my dose of T3 and take once a day with one glass of water. I am fortunate.

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Advice on here is take t3 8-12 hours before blood draw even if it means altering the times you the it the day before. I always leave it 10 hours, lol, bang n the middle 🙂

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I still take blood draw 24 hours after T3 dose as I am not changing time when I take my dose neither do I split daily dose.

So far I have had no problems, except when GP a couple of weeks ago phoned to say my TSH was too low, Free T3 too high and FT4 too low and to lower dose.

I said to him "I didn't know you were doing a blood test so by taking hormones a short while before those results will be skewed". I said look at my previous test which was taken 4 weeks ago, so he looked and agreed. Before that he said but T3 converts to T4 so T4 should be higher and I said 'No - its the other way around.

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Ha ha ha! You've got a pearl, there, shaws!

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Thanks again!

I’ll give that a go.

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The very best way to judge if dose of thyroid hormones (whatever a person takes) is 'how we feel'.

I shall give you a link to an archived post and his patients who were resistant to thyroid hormones always took T3 only - others were prescribed NDT.

Many doctors panic when they see our results as blood tests were invented for levothyroxine (T4).

web.archive.org/web/2010103...

I responded to another post earlier re T3.

healthunlocked.com/thyroidu...

GPs and Endos have been told not to prescribe T3 (in UK) as the cost is now prohibitive.

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You want to obtain an approximation to your average fT3 levels whilst on L-T3, this is difficult due to the short elimination half life of T3 (up to 24 hours). The best you can do is have the blood taken half-way between two L-T3 doses, so if you take your liothyronine twice daily have the blood taken five or six hours after your morning dose. Your TSH will not be suppressed unless you are on a high dose, 50 mcg is quite a resonable dose so I would expect a low TSH but perhaps not suppressed.

T3 is required for thyroid hormone action but some organs are able to convert T4 to T3 and so are not reliant on circulating T3. Normally fT3 and fT4 are mid-interval in healthy subjects and they benefit from both the T3 and T4. For someone on L-T3 only it would seem reasonable for fT3 to be in the upper half of the interval because their fT4 will be low and won't be able to contribute to hormone action. (This is my judgement, not evidence based).

If you need L-T3 only therapy it is probably because there is some malfunction in your thyroid system (my vagueness is deliberate). In this case you may not recover with normal hormone levels and so you and your doctor should pay very close attention to signs and symptoms and adopt a cautious approach but you may need supraphysiological doses that suppress the TSH. This treatment is not ideal but ideally you would not have a thyroid problem in the first place.

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Thanks Jimh111 & Shaws

I will absorb these 2 posts & rely later.

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Repeatability is the key to testing anything. The aim is to control as many of the elements known to affect your thyroid hormones and do the same every time you test.

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As others have said, the goal is to feel well, not get the right test results :)

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