Curious question about T3 and testing

[Lenaa]

If T3 is short acting and is gone within a few hours and we test first thing before meds, how can we ever see optimal T3 in a test? Surely much of it is gone overnight?

[jimh111]

T3 has an elimination half-llife of about 24 hours. It's difficult to measure fT3 if we are taking T3, the best I can suggest is to have the blood taken about half-way between doses.

[Lenaa in reply to jimh111]

so how is one supposed to know if one is optimal..? I'm confused

[jimh111 in reply to Lenaa]

‘Optimal’ is a term I dislike, for most people it will be average levels but for a few can be quite high. Optimal is often used to mean high levels which are not optimal for the general population.

[Hidden in reply to jimh111]

I have to have my ft3 over 80% after taking it 24 hrs earlier, so I completely agree. For someone else this may be way too high. But to be able to get to this level it took me over a year and the work is still in progress. When you get closer to "optimal" you certainly feel it, but for many months before it feels like nothing sometimes..just shows how hypo we can all be

[jimh111 in reply to Hidden]

Some patients need supra physiological doses of T3, it’s important to identify these cohorts so therapy can be better targeted.

[Hidden in reply to jimh111]

This is why I believe past researches that state t3 is useless have failed , because on how they dosed patients, according to TSH, or ranges, not thinking that possibly some people need more. A trial, when people take as much as they need to restore health would be desirable!

[Batty1 in reply to jimh111]

Why is it difficult to measure FT3 when taking T3, I have never heard that on here?

[jimh111 in reply to Batty1]

I should have said difficult to assess. It’s easy to measure fT3, just do a blood test. However, if you take T3 medication there is a wide variation in fT3 levels with a spike about three hours after the dose.

We don’t know how tissues respond to varying T3 levels. Do they respond to maximal, minimal or average levels (area under the curve)? So when do you take the blood? My best guess is to take the blood about halfway between doses in order to get a rough average.

The other rough guide I use is that L-T3 is about four times as potent as L-T4. So, if I take 20 mcg L-T3 I assume it is equivalent to 60 mcg L-T4.

[wellness1 in reply to jimh111]

Many take their split doses 8 hours apart. So you would suggest testing after 4 hours? But that would measure a value closer to the peak than a rough average, no?

[jimh111 in reply to wellness1]

The peak is around 3 hours after ingestion but for 8 hourly dosing I would leave 5 hours just to be safe. If you are taking liothyronine 3x daily the spikes are much smaller so timing is less important.

[Lenaa in reply to jimh111]

Do you need to take T3 away from food as well? If so, that makes it hard to manage three times a day. You can't eat when you want or need to

[jimh111 in reply to Lenaa]

L-T3 is much better absorbed (95%) than l-T4 (~50%) so should be more rapidly absorbed although there have been no studies of the effects of food on T3 absorption.

I take my L-T3 about five minutes before breakfast, an hour before dinner (if if you live in the North) and at bedtime. Just avoid taking L-T3 with large meals, coffee or bran and it will probably be OK.

[Lalatoot]

What is optimal FT3? If you want to see it at its peak test 2 - 4 hours after a dose. If you want to see it at a low point test 8 - 12 hours after a dose. It depends if you want to measure the high or the low of the cycle. It is either on the way up or on the way down it never stays at a certain level.

[helvella Administrator in reply to Lalatoot]

Trying to get a peak measurement is very difficult. It changes very rapidly on the way up, peaks, and then fairly rapidly down. A few minutes could make a clear difference to the measurement.

Whereas in the time leading up to the next dose, the rate of change is much lower.

If we had a continuous T3 monitor, I think it would show this clearly. But we don't. So the next best is to measure in the trough before the next dose when the rate of change is at its lowest - a few minutes, an hour or more, would make the least possible difference.

On the basis that the pattern will be much the same every day, we can compare one day's measurement with another. And see how it changes.

In other areas of medicine this is very well appreciated and the medics specify trough readings.

Another possibility is a fixed time after taking the T3. Precisely how long is arguable.

There is much more discussion here:

thyroidpatients.ca/2019/11/...

[diogenes Remembering]

The T3 spikes after dosing may not be dangerous at all. It takes time for the body cells to respond, by which time the spike will have declined, and henceforward the apparent effects of the short time" overdose" will also die down to be replaced by a more normal level . Therefore though the T3 spikes appear dangerous, in fact they may not be so, because of the delayed response of body cells to it. This will lead to "waves" of FT3 effects in the cells whose peak is lower and lasts longer than the T3 peak and which stabilises the length of the effect much longer. It's called damping.

[asidist in reply to diogenes]

sorry to kind of be veering off topic here but with all this talk of spikes and variation, wondering if there’s any good reason we don’t have t3 skin “patches” that continuously release t3, much like birth control patches? seems like something along those lines could be really helpful

[helvella Administrator in reply to asidist]

Thyroid hormones do not pass through skin sufficiently.

Also, patches are not good at achieving precise dosing. Thyroid hormones require consistent and accurate delivery.

[asidist in reply to helvella]

plenty of good reason then. thanks helvella.

[Meanbeannyc in reply to asidist]

They have slow release T3 from compounding pharmacies. Idk where you’re located but can easily be ordered online.

[asidist in reply to Meanbeannyc]

thanks i’ve heard of of compounded slow release T3 on occasion but never thought much about it. i do use a compounding pharmacy to make t3 for specific reasons but haven’t considered it for daily dosing - i’m a bit wary of mistakes that could be made by the compounding technician at any time and feel more comfortable using regulated, pharma t3 on a daily basis. it’s an interesting idea though. have you tried the slow release and noticed a better result? is methyl cellulose powder the ingredient that slows the release?

[Meanbeannyc in reply to asidist]

Never tried the slow release no, I know someone who loves it though.

[shaws Administrator]

I love T3 - it suits me and I don't need a large dose. My 'optimum' is a dose that relieves all clinical symptoms.

[mandy-white in reply to shaws]

Would you mind if I asked how much you take . X

[shaws Administrator in reply to mandy-white]

My dose, at present, is 25mcg. I have taken not too much higher doses but I take more notice of my clinical symptoms and adjust if necessary.

On this forum we are more aware of taking notice of the TSH and FT4 and FT3, A TSH of 1 or lower and the Frees should be towards the upper part of the ranges.

'Once upon a time' - before blood tests and levothyroxine - we were diagnosed upon our clinical symptoms alone and prescribed NDT (natural dessicated thyroid hormones) and we may have been given some T3 added to T4 if we were taking levothyroxine only.

Quite recently they removed T3 from being prescribed - even though lots of researchers found a T3/T4 helped many patients. They also removed NDT (natural dessicated thyroid hormones) through misinformation about it - that saved lives from 1892 onwards and yet, here we are in 2020 where we cannot trial anything other than levothyroxine. Doctors/endocrinologists have to follow their guidelines otherwise they will be reprimanded by those who should know better but don't.

[NWA6]

Optimal is when you feel well not necessarily a number. The numbers are there to guide and to make the medical professionals feel like they know something because they can’t take your word for it that you feel crappy. It is actually a fact that patients lie all the time. What the medical professionals don’t seem to understand is why patients lie. The relationship between doctor and patient is one of a power imbalance.

Anyway I digress. When you take your blood tests at the same time every blood test then you’ll find your number. You can adjust accordingly and become optimal - if you stilll need a number to focus on. When you become in tune with your body you’ll begin to know without numbers. I always do my tests 8hrs after taking half my dose.

[FancyPants54 in reply to NWA6]

Do you split your dose or take it all at once on a normal day?

[NWA6 in reply to FancyPants54]

Is this question for me? Just in case it is, I split my T3 10 x2, morning and night and now just added 5 in the afternoon. Levo I take at night.

[FancyPants54 in reply to NWA6]

Yes, my question was for you. Thanks.

[Lenaa in reply to NWA6]

do you take away from food like T4? I need to snack often and it's very hard to manage if it's so many times a day of not eating

[NWA6 in reply to Lenaa]

Not really in the morning, I usually have a coffee about half an hour after taking, sometimes 5 mins after. Doesn’t seem to make a difference. T4 is at night so probably about 2/3hrs or more after eating. I added my extra 5mcg in the afternoon to begin with but now take it at night with the other 10mcg

[shaws Administrator]

One dose of T3 lasts between one to three days. I take it, am well and have no clinical symptoms.

I take one daily dose when I get up a.m. but when having a blood test I have the earliest appointment and take T3 afterwards. I've always done this method

[FancyPants54 in reply to shaws]

You dose it like we would T4 then. I have tried the split doses recommended by Paul Robinson in the past and not felt better despite getting to a quite high dose. I'm wondering if I'd do better taking it all at once to get some into the cells for the day.