FT3 testing.

[lucylocks]

Hi

My daughter is taking T3 only, she has recently reduced her dose so is going to order a private test.

Last time she just ordered the FT3 test as I thought as she takes T3 only her TSH would be suppressed and T4 low anyway, am I right in thinking this ? or would it be best to have TSH T4 tested along with the T3.

Also how long after a dose reduction is best to wait before testing to get a true T3 level and do you leave 24 hours from your last dose before doing the test and is it best to fast for 12 hours.

Many thanks browny

[Clutter]

Browny, if your daughter is taking more than 40mcg T3 her TSH and FT4 are likely to be suppressed and only her FT3 needs checking. 12 hours after last T3 dose is long enough but others will say 24 hours. Fasting is recommended when TSH is measured as it is lower before food and drink, other than water. If your daughter is self medicating she doesn't need to fast.

[lucylocks in reply to Clutter]

Many thanks Clutter for your reply,

She reduced her dose a week ago so will it be O.K. to test in the next few days or should she wait longer. I know T3 gets out of the system pretty quickly but not sure how long to wait after a dose reduction to get a clear picture.

Thank you.

[Clutter in reply to lucylocks]

Browny, 4-6 weeks after dose adjustment to check levels.

[lucylocks]

Hi Clutter,

I thought that was for levo.

I thought it was different for T3 or have I got that wrong ?

[Eddie83]

There is some confusion about the half-life of T3. In my case, I found it to be approx 12 hours (as the result of testing while I was on T3-only), but there are refs on the web that say the half-life is up to 2.5 days. The rule of thumb is that you wait 5 half-lives after a dose change, before testing.

It would be best to test TSH also, just to make sure it isn't too low. The AACE range of 0.3-3.0 is better than the common 0.5-5.0 range used by most labs, although I've seen some functional medicine practitioners recommend that it's OK to let TSH drift down to as low as 0.1. Don't let her get lower than this; if there's one thing that is worse than hypothyroidism, it's hyperthyroidism.

[lucylocks in reply to Eddie83]

Many thanks for your reply,

Do you happen to have any links to the references on the web, I have been searching and I cannot find anything.

I have just ordered my daughter a test for TST T4 T3 and she reduced her dose about 10 days ago so by the time it comes she should be O.K. to do it by your estimation.

Thank you again browny

[Eddie83]

You would think that en.wikipedia.org/wiki/Lioth... ought to be reasonably authoritative, but that site claims the biological half-life of liothyronine is 2.5 days. Which does not match my experience, or what I've been told by my doc.

You could try googling "liothyronine half-life". Many of the refs state a half-life of 2.5 days. The question is, does your daughter want to wait as long as 5*2.5=13 days for retesting? If she's willing to wait that long, then you can be sure that you've reached a steady state after dose change.

[helvella in reply to Eddie83]

Whilst some of Wiki is amazingly good, it does have lots of things that are questionable.

Half-life of a substance in a complex biological system is very different to radio-active half-lives. In a hypothyroid person, the effective half-life of T3 is much shorter. And in a hyperthyroid person, it can be much longer. Further, whereas radio-active half-lives can be shown to be phenomenally stable with a literal halving in every half-life period, with T3, it also depends on how much is in the system.

[lucylocks in reply to helvella]

Thank you for your reply helvella.

[lucylocks]

Hi

Thanks again,

well she is actually feeling worse but instead of raising her dose we thought would get her tested to have insight of what's going on.

In June she was on quite a high dose of 100mcg, and her T3 was over range. I do not have the figures with me as she does not live with me but I think top of range was 6.8 and her level was maybe 7.6 so she reduced to 50mcg.

She did not have any over dose symptoms.

She recently reduced to 25mcg. as she was getting episodes of loose stools and sweating but she is now back to sleeping all day so the reduction has made her feel worse.

Maybe the tests will hopefully tell us what is going on.

[faith63]

Yes..and there is no need for thyroid testing, when on t3 only, as they don't loo normal. You go by relief of symptoms only.

[lucylocks in reply to faith63]

Thank you faith,

Should we not worry then when the T3 is a little over range.

When she was on 100mcg. of T3 she felt good with no hyper symptoms at all but she reduced as level was over range.

After a few weeks on the reduced dose she started feeling very hot with stools loose so has now reduced further.

It is quite puzzling as if the symptoms were due to the T3 why did she not get them on 100mcg but got them on 50mcg.

I have come across" Wilson' Temperature Syndrome" this evening and found it really interesting.

He treats patients with T3 when they show symptoms of hypo, (but blood levels are in so called range) because they have low body temperature.

My daughters temperature has always been low.

[faith63 in reply to lucylocks]

I would contact Shaws on this forum, about Dr. John Lowe and his use of t3 and links to information. He found Wilson's totally useless, as some, like me and your daughter, have low temps, that stay low and have been low for many years, before the thyroid symptoms showed up. Thyroid meds don't raise my temps. But since getting Hashimoto's, my temps are not stable, sometimes i feel feverish, but am normal.

Many people have thyroid hormone resistance and need a dose that causes the ft3 level to be shockingly high, in order to relieve symptoms, yet they have no hyperthyroid symptoms at all and feel better/well.

T3 is dosed by improvement of symptoms, not labs or the dose would always be kept too low. As you see, she felt well and is now ill, upon a dose reduction that is based soley on labs. Most on here, on t3 only, have to buy their own meds online, because doctors will not let them dose to the point of doing well. This doctor will keep her ill.

[faith63 in reply to faith63]

Again..never, ever is t3 only dosing based on ft3 labs. It defeats the entire purpose.

[lucylocks in reply to faith63]

She is actually self medicating.

It was me who panicked when her T3 was over range but it seems she should have stayed on that dose, I just thought it seemed a big dose to be on.

So as long as she does not get any overdose symptoms she is O.K. to stay on a high dose.

I have read Shaws posts about Doctor John Lowe. I will do more research into his methods. Thank you.

Are you on T3 and how are you doing ?

[donna]

Hi browny

[donna]

Hi browny it's good your daughter has you in her corner... I've read this discussion and agree with all the threads .i just wanted to add that when reducing or increasing T3 do it gradually and in small increments ..harder I know with some tablets to get a half or quarter tablet ,some are marked but I've have found a razor blade helpful for cutting... To big a rise or fall in T3 dosage causes. Shock to the system .... Slowly does it ... Also it won't wirk correctly if all your daughters other body building blocks are low ... Vit D Iron B12 magnesium +++ all need to be at optimum levels for the T3 to work correctly ...( you mentioned sweating) ... Hope she gets sorted soon .

[lucylocks]

Hi Donna,

Many thanks for your reply,

my daughter takes all the recommended supplements and more besides.

Her iron was very low at one time but she continually supplements with it otherwise if she stops it her level drops again. She also uses progesterone cream for her PMT which she has had some success with.

Were you suggesting something may be amiss which is causing her sweating ?