I've been messing around with T4 and T3 combinations for about 18 months now, I think.
For a bit of potted history, I'm a horrifically poor converter.
On 100 mcg T4 + 2 x 5 mcg T3, I am still tired with brain fog. When I tested, my ft4 was lower than it is on 100 mcg T4 only by 20%. My fT3 is less than 50% through range at peak serum level. It doesn't feel like I'm taking enough T3 in one go for it to make any difference or reach my cells. I sometimes also feel slightly jittery on this level and TSH is below range, so my general feeling is that I am getting too many thyroid drugs without getting enough of the right ones! If I take 10 mcg T3 all at once on 100 mcg T4, I just feel like death.
On 75 mcg T4 and 10 mcg T3 all at once, I feel amazing for 2 to 3 days. After that, I feel rubbish. It is the second time I've tried this dose (nearly a week this time around) and the same thing has happened both times. Last time, when I tested, my fT4 had sunk to 20% through range.
So, I need a big dose of T3 to get the benefit of it, but that big dose makes my body worry about being over medicated, so bless, it compensates by dumping a load of T4 and probably converting it into rT3 and making me feel like rubbish!
I think there are potentially 2 solutions to this, so I'd like to ask for thoughts!
1. Drop T4 dose by 12.5 or 25 mcg. If I haven't got a load of spare T4 circulating, then my body can't convert it into rT3, can it?! I assume I might find I need a bit more T3, either in the morning or afternoon in the longer term.
2. Split the dose of T4 and take it in the evening and the morning - again, less at once should presumably mean there's less "spare" to convert to rT3? Or would it?
Basically, I think I need a more NDT style of dose - as in high levels of T3 medication and lower levels of T4. And frankly, I've never tried, so worth a shot...
Thanks for any thoughts or anecdotes! I'm particularly curious as to whether anyone else experienced their body throwing T4 off a cliff when they took enough T3?! What did you do?!
Lotika x
(PS: vitamins: B12: super optimal; D: almost perfect; Ferritin: good by my standards, but not great (71); folate: fractionally sub-optimal and therefore a work-in-progress; vitamin supplements, yes, many.)
Written by
Lotika
To view profiles and participate in discussions please or .
My advice is allow at least a week to acclimatise to any t3 dosing change (others will say more) and secondly does it actually matter if your t4 is low? I know it does to some but I e given up worrying about it now and try to focus only my on t3.
True - my endo says 3 weeks to stabilise a dose when altering T3... And I agree that if (oh, if!) fT3 is right then the amount of fT4 needn't matter... I think this is why I'm figuring dropping the amount of fT4 I take can't hurt. Let's face it, my body barely does anything useful with the stuff anyway!
And I know I’m always saying this but my body never accepted 5s and 10s of t3 - it was only comfortable when I started on 20 all at one with my t4 first thing in the morning. There is a theory I believe about flooding your receptors and I don’t know the science but that’s how it felt to me. I took to it straight away. Tried 5/5 then 10/10 splits and my ears and head hurt all day then went to 20 all at once and felt fine. Now I’m just one person so there’s nothing scientific in any of that! I now take 25 t3 each morning. I can Switch it to 30 no probs and reduce it to 20 (no probs but no bowel movements ever ever). I take 100 Levo but also tried a few weeks without it and saw no difference. I added it back as I’m prescribed it but think it’s prob the t3 doing all the work.
On 100 mcg T4 + 2 x 5 mcg T3, I am still tired with brain fog. When I tested, my ft4 was lower than it is on 100 mcg T4 only by 20%.
Your FT4 will be lower when you add T3, that's just what it does so the 20% drop in your FT4 is to be expected.
My fT3 is less than 50% through range at peak serum level.
If it's only 50% through range at it's peak then that suggests you're not taking enough.
On 75 mcg T4 and 10 mcg T3 all at once, I feel amazing for 2 to 3 days. After that, I feel rubbish. It is the second time I've tried this dose (nearly a week this time around) and the same thing has happened both times. Last time, when I tested, my fT4 had sunk to 20% through range.
Taking T3 will reduce FT4, also you reduced your dose of T4 so it's no wonder your FT4 level reduced so much.
it compensates by dumping a load of T4 and probably converting it into rT3 and making me feel like rubbish!
Have you tested rT3 to know that?
The only thyroid related reason for high rT3 is when there is an excess of unconverted T4 and with your FT4 just 20% through range there's very little possibility of any excess unconverted T4. But even if you did have high rT3 it doesn't last long in the body, it moves on by deiodination to T2, T1, etc.
You seem to be focused on rT3, I think you're on the wrong track there, as I mentioned you don't really have any "spare" T4 to convert to rT3.
Thanks, SeasideSusie! I'm at a loss to understand why I feel better initially when taking T3 all at once, and then worse. Previously, when moving doses to 10mcg T3 + 75 T4, I upped my T4 to get there, rather than dropping it and still saw it get lower. This could have been antibiotics. So, my rT3 idea - and I did find some stuff on it today, but know it is controversial - explained what I am currently feeling again. That I was initially better, but am now worse for the dose change. Admittedly, last time it could have been antibiotics and this time it could be something else random? Or the fact that I did drop the T4. But I feel rubbish if I take T3 in one go on 100 mcg T4 too, which I don't have a way of making sense of either. What do you think is happening?
There are a lot of outdated ideas floating around about rT3. These are the reasons rT3 can be high:
High rT3 can be caused by many things, only one of which has anything to do with the thyroid and that's when there is an excess of unconverted T4 and you will know this from the FT4 and FT3 results, you don't need a rT3 test to show this.
High rT3 could be caused by low ferritin, by an infection, by low-calorie diets, selenium or zinc deficiency, cortisol issues, stress, dieting, chronic illness, inadequate or low iron, chronic inflammation, high cortisol, or liver issues and any other chronic health issues, and probably several more things.
Other conditions that contribute to increased Reverse T3 levels include:
· Chronic fatigue
· Acute illness and injury
· Chronic disease
· Increased cortisol (stress)
· Low cortisol (adrenal fatigue)
· Low iron
· Lyme disease
· Chronic inflammation
Also selenium deficiency, excess physical, mental and environmental stresses. Also Beta-blocker long-term use such as propranolol, metoprolol, etc. Physical injury is a common cause of increased RT3, also illnesses like the flu. Starvation/severe calorie restriction is known to raise RT3. Diabetes when poorly treated is known to increase RT3. Cirrhosis of the liver. Fatty liver disease. Any other liver stress Renal Failure. A fever of unknown cause. Detoxing of high heavy metals.
Well I can't say for definite but maybe some of the following is involved:
You mentioned in previous post you're very poor at taking second dose of T3 and you were advised that it must be the same dose every day.
How often have your doses been changed, how long between changes? Levels can take a long time to settle after a dose change.
You have Hashi's which is always going to make things difficult because of the fluctuations that Hashi's causes.
It can take years to find the right combination. I added T3 to Levo at the end of 2015. At one time my T3 dose was 31.25mcg. Now, 7 years later, I've found what's probably my best doses and I take 12.5mcg T3.
I'm at a loss to understand why I feel better initially when taking T3 all at once, and then worse.
That is perfectly normal, and just means you're ready for an increase in dose of T3. Leaving three weeks between increases seems a bit excessive to me, we usually increase after two weeks. And it sounds as if you need to increase sooner rather than later. But, not too soon.
Taking T3 will reduce your level of FT4. That's the way it works. No-one seems to know why, or what happens to that lost T4. Could be that it's converted to rT3, but I doubt it unless you're taking a pretty high dose. rT3 is a total red herring, anyway.
Whether or not it matters if your FT4 drops is a very personal thing. Myself, the FT4 is best at zero! But, others need it quite high in range. But, get the T3 dose sorted first. They you can worry about the T4.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
Should I increase my T3 or my T4?
Success! Folate supplement has finally increased my T4 to T3 conversion!
What else can I do to raise my T3 to optimise it to 70% in range?
How much T3,t4 body still produce when on NDT?
When to do tests when on T3 only?
