I would like to understand why, in a variety of circumstances, FT4 depletes during thyroid therapy. In my own case, my FT4 and FT3 both fell over 3 years on the same dose of NDT. In other cases that I have read about here, FT4 depleted on the same dose of T4 when the dose of T3 was increased.
At the beginning of my thyroid therapy (before this no treatment) my TSH became suppressed very quickly. My FT4 became just under 50% through range and my FT3 became 76% through range. My TT4 started out 40% through range. It was perfect. I felt fine. However over the 3 years in question on the same dose of NDT (which was 2.5 grains thiroyd divided 1.5 morning and 1 afternoon), I watched my FT4 go down to a little under range and my FT3 fall to 43% through range. My TT4 also fell. I don't have hashis. I am probably central hypothyroid although never diagnosed by a doctor.
The 1st question I have is - why did my FT4 deplete over time on the same dose of NDT (ratio 4.2 T4:T3)? What's the science?
My 2nd question is - why did my FT3 fall too? Why did my FT3 did not maintain itself at 76% when I was dosing the same NDT?
It can be observed in some people that the lower the ratio of T4:T3 dosing, the more FT4 depletion in the blood. I am now starting again and this time I have synthetic T4 and T3 in my arsenal as well as NDT. On one grain of NDT (Armour) and 62.5 T4 (ratio T4:T3 = 11) I achieved blood results of 39% FT3 and 44% FT4. This is about the same FT3 that I got on 2.5 grains thiroyd. I wonder if this is because my body is making up for less T3 in dosing by getting more FT3 from conversion of T4? I am now not sure how to proceed as I still feel hypothyroid. I am about 75kg weight. I get a racing pulse and heart arrhythmia if I raise T4 much beyond 100mcg. If I raise T3 then I suspect I'll just get T4 depletion again. I'm not actually sure how much it matters in my case if FT4 is under range if I could get FT3 right. I don't know where to go from here, but if I understood what happened the first time around I think I'd have a better chance of making educated guesses about my dosing going forward.
On Thyroid Patients Canada website : thyroidpatients.ca ,there are some very pertinent blogs by Tania Smith addressing ratios and the science, if you scroll down them. I've studied the information there but I still can't get my head round this T4 depletion thing or how to deal with it. Any light you guys can shed would be very welcome.
Thanks, June
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June25
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Hi June25, your post is being read but probably few could answer you ‘ scientifically’. I am just a few years younger than you, and had a Hashi( high TgAb only) hypo diagnosis 20 years ago, yet am still struggling to get thyroid bloods right, never mind feeling good. Age and other ailments ( including insulin dependent diabetes and fibromyalgia) have added to the problems. After years of self help ‘tinkering’, adding T3 to levo., getting mins/vits ideal etc, I have recently seen a forum-recommended endo( on zoom) to see if he can figure out what is wrong. So yet another slow , and expensive, journey ahead…. Be interesting to see how much ‘science’ is involved compared to trail and error!
Many thanks for your reply. It's not easy, is it. I've often thought about going to an 'expert' like you are doing now but never taken the plunge. Good luck with that though. If it works out for you please pm me with details and I'll go for it too.
For any thyroid hormone replacement to work well we do need to maintain optimal ferriti, folate, B12 and vitamin D and conversion can also be compromised by any psysiological stress - either physical or emotional, inflammation, chronic pain, dieting, depression and ageing.
I am taking NDT these past 3 years and my T4 comes in around 25% / 30% with my T3 at around 90/110 % and I am with no hyper symptoms, and if anything still with some hypo symptoms. I take a yearly full thyroid panel more for my vitamin and mineral levels than my thyroid.
With NDT you dose to the relief of symptoms and not a blood test and fully expect, as I age, that I may have to adjust my dose.
The blood tests and ranges and guidelines were introduced to be used with synthetic thyroid hormone replacement and would think deciphering an NDT / Levothyroxine / Liothyronine combo blood test very confusing and think it best to go with, hopefully, symptom relief.
When on T4 only medication the accepted conversion ratio is said to be: - 1 - 3.50 - 4.50 : T3 / T4 : with most people feeling at their best when coming in at 4 or under.
So you simply divide your T3 into your T4 to see how well you are converting but this doesn't apply when taking anything other than Levothyroxine.
I don't think you can simply equate the T3 and T4 in NDT as equal to that found in synthetics but I guess it might offer a of ball park of levels to work in or out from depending on how you feel.
I'm Graves post RAI thyroid ablation and now managing lingering Graves, thyroid eye disease and hypothyroidism.
Hi pennyannie and thanks for your reply. I agree that symptom relief is the goal and that synthetic T3 and T4 are not the same as NDT.
The definition given in the STTM book 'Stop the Thyroid Madness' for the optimal dose of NDT is:
- a mid afternoon temp close to 37C.
- the near complete elimination of hypo symptoms which lasts - does not go away.
- An FT3 towards the top part of the range and a FT4 around midrange, both.
Ofcourse not everybody gets there for a variety of reasons. One theory in my case is that I didn't raise my NDT dose high enough to be durable over time. I couldn't because my heart rate went up too high at 3 grains. ( I have high cortisol).
Hi , I always want to understand the 'mechanics' /science of how a thing works too , and am a fan of Tania's ThyroidPatients.Canada blog (i find the pictures very helpful lol ) ....... but i think the answer to your question about T4 reducing when T3 is added is really that the 'science' hasn't been done yet .... it's just an observation that people who see lots people's thyroid results have made. When you add T3 the T4 quite often goes down but not always
Logically if the TSH lowers more due to the influence of added T3, then less TSH= less thyroidal T4 production, so that may partly explain it in some cases ?, but not all , as it still happens even when people have no thyroid i think.
As with so much of 'thyroidology' there is not much recorded data for anyone to go off to further the 'science' because they don't measure FT3 often enough in hypothyroidism to see the patterns .
Same with antibodies .. lots of autoimmune hypothyroid people will have some TRab of one sort or another , but no one looks for them, so .... no data.
When you then add the fact that everyone is so individual in their response to different types. levels , and ratio's of thyroid hormones , It makes it even harder to understand 'Why does that happen ?'
Also , so many of the recorded thyroid results come from people with autoimmune hypo ,, so that in itself adds fluctuations that mean you can't prove with any certainty which action caused which result.
Science can only take you so far with thyroid hormone replacement .. it has been said that "it is more art than science" .. and i think there's a lot of truth in that.
I also think it is largely a case of 'suck it and see' to find what works for you .
As long as we always bear in mind that the body's HPT axis is constantly trying to keep the T3 level stable, as it's main priority above everything else, and therefore very small , gradual adjustments are going to get better results than chopping and changing what we give it to deal with .. then 'suck it and see' is often as scientific as it get's in terms of understanding what happens to you when you change something about your dose.
Hi tattybogle and many thanks for your reply. It is so frustrating but I think you are right that either the science has not been done or it is not in the public domain to find out. Frustrating because I know there is an answer to this question. If Tania Smith can find out so much helpful information about the mechanics of Dio1 / Dio2 / Dio3 then why not T4 Depletion. This information can really guide people to avoid dosing mistakes and save time with the 'suck it and see' approach. Honestly, given all the permutations and combinations to try I sometimes wonder if I'll die before I get there.
Anyway, getting off my soapbox, I really like what you say about very small and gradual adjustments. Patience is not one of my virtues but in this case I have to accept that there's nothing else for it.
That would be ironic wouldn't it " hey, i've found my ideal dose combo .... and it's my 98th birthday.. hurrah!"Thyroid has a way of teaching patience. If you keep changing stuff too fast , life just knocks you on your ass and sends you back to the beginning till you learn to wait longer , observe more, go slower , make smaller changes , wait longer to see what improves.
Same thing works with adding stuff and changing environment to getting plants to grow better, bigger, healthier flowers.
Longer .
Slower .
Less.
Have you though of asking Tania a direct question about it ? She might have inklings of ideas she hasn't written about yet.
Ha ha, that's exactly it. Dead of old age and still working on it ):
I've emailed Tania already about this. They have a Facebook forum but I don't like to put anything on Facebook, don't trust it.
Well I've been knocked on my ass once so far and sent back to the beginning, and that's taken the whole of 2021. I'm paying attention closely to what you say about taking it slowly and it feels right, an organic approach. I lack self discipline though, so seeing your words written down might help me in times of temptation, so they're important.
I'm the type who just has to do something, so maybe I'll turn my attention to researching everything I can find on ways in which T4 can be dissipated in the body. It seems like there are only so many slots in the body available and when there's competition for a slot T3 wins and T4 is displaced. So for people who can't get to optimal FT3 / FT4 (ala STTM) maybe it's not just the ratio of dosing that matters, maybe the number of slots there are has to be somehow increased to make room. That would be the HPT axis that needs to get the message I suppose, but how? Or maybe you just go with T3 and hope for symptom relief. That works for some. Too many theories, too little information, too little time.
Yes, learning and researching is a great way to pass the time while you're practicing the "if in doubt ...longer ....later.... less " mantra.
If you hang around on here often enough you can sit back and watch other people make the mistakes for you , and watch them go round in circles when after 3 weeks they don't feel any better and they change something else.
I think the idea that there is an optimal T4/3/ TSH level to aim for 'in treatment' is too simplistic and ignores how individual we were 'in health' Presumably it's much more likely that we will feel well if we can get something like what we had in health .. which of course is information that most of us don't have, as we don't become interested in our T4/T3 /TSH until were 'broken'.
To some degree it's impossible to perfectly recreate 'healthy' ratios on treatment as the very fact of adding T4 in a big lump changes the relationships.
But i'm quite sure some people would not feel well on the 'optimal' levels STTM suggest aiming for , and would then not understand why they don't feel right when they have 'the right T4/3 % '
See how different this lot below are .. and imagine how many more differences/extremes you might find if you tested more than 10 people ..
6 of them are used to having higher T3 than T4. (which you won't often get from Levo alone)
5 of them are used to having both T4/3 well below 50%
only 1 of them is used to having both above 75% (with a curiously 'high' /fixed TSH )
Ha - how many times have I wished that I had my thyroid figures from before my thyroid issues. Even asked my doc to look back but they didn't keep them that long. Anyway they wouldn't have done FT3. I tell the young people that I know to get full blood panels of everything before they are 25, so much easier nowadays, but would I myself have listened back then, I don't know.
I am 'hanging around' here more and more because I find that I always come away having learned something. I do agree with you that there are big differences between people and each one's 'optimal' will be correspondingly different. I still find it useful to at least have some goalposts set up and find some things to focus on rather than be floundering in a sea of infinite possibilities, even if that's the actual reality.
This stuff can drive you crazy. I'm visualizing your image of plants growing slowly, better, healthier. It's working for me.
if you want one to perform really badly , keep messing with it's environment , and add slightly more 'expensive plant food' than the instructions suggest, cos you think 'more must be better' , and then go online and post a picture of your now sad, puny, crispy looking plant, and ask everyone "what's wrong with it ?" and 9/10 of them will tell you " get some of this or that and feed it that cos it's lacking in so and so, and you'd do better to buy bat guano compost from Bolivia or else you won't ever grow anything good ...."
Meanwhile the 1/10 is an old codger with mahoosive flowers every year , grown in whatever compost he had to hand , who says , "pay attention to the environment it likes and keep it stable , they don't like sudden changes, it stalls their growth, get the humidity optimal ,and the temperature optimal , and sort out your ventilation/shade to keep it that way, dilute any plant food to half the recommended concentration, .. and if in doubt ...... feed less , wait longer , harvest later ..... "
Buy a nice plant .. and watch it every day ... that will also help you pass the time.
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Bloods on NDT - Low T4
On combined t3/t4. FT4 and FT3 at bottom or out of range but increasing the dosage is barely raising the blood test results, TSH suppressed
Should I split my T4 dose? 
What's going on?
Comments on latest blood results please.
