Hi all, I’m trying to do some detective work on my recent blood tests following introduction of T3 to complement my T4.
Does anybody have any credible research articles or other sources which indicates how much (if any) impact adding T3 has on TSH?
I’ve read some things on the internet which say only T4 impacts TSH but also some to the contrary. Some articles say “thyroid hormone” which isn’t really conclusive!
Many thanks in advance
Do you not find your latest blood test results from adding T3 to levo rather conclusive evidence that adding T3 has lowered your TSH ?
Did you really find someone saying that "only T4 impacts TSH" ?
That's so illogical i don't really know where to start....... Yes T3 (and T4) does impact on TSH.
Well yes and no, because one test was 9am fasting and the second was 1pm non-fasting.
In addition my T4 has gone up despite stable dose and my TSH has historically jumped around on stable dose of T4 only and consistent 9am fasting tests (apparently common with Hashi’s).
If you really need convincing that T3 has an effect on TSH, you could look up some posts on here from the people who take T3 only, if there was no effect they 'd all have high TSH.....and no arguments with the doctors about supressed TSH.... which would make life really easy for them .... but sadly that's not what happens.
Even taking the annoying randomness of autoimmune thyroid results into account, your own results do still suggest T3 addition is reducing your TSH ... you have a previous fT4 at 22 on 150mcg levo , and TSH at that one was 0.11. (fT3 was 5. something) Now you have fT4 at 22 again on 150 Levo + some T3 and TSH is 0.03 ( ft3 is 6. something)
Well this is my point.
On T4 mono I have 2 results of FT4 at 22.9 but the TSH was 0.72 and 0.11. So the same dose of T4 can give the same FT4 result but quite a bit different TSH. This must be the Hashimoto’s variation in TSH.
I’ve had another set of tests where FT4 was 20.0 and TSH was 1.58.
So again quite a bit of variation despite no change in medication.
Now with the introduction of T3 in addition to T4 my FT4 is 22.3 but TSH is 0.03. Yes of course FT3 has jumped from 4.3 to 6.9.
So actually, ignoring the result in October, despite adding T3 therapy my FT4 is only slightly down (from 22.9 to 22.3) and my TSH is only slightly lower (0.11 to 0.03).
So I don’t consider taking T3 has actually had any dramatic impact on my TSH level.
Which is why I’m puzzled and trying to factor in how much is the real change and how much is the jumping about effect from Hashimoto’s.
Between you and me ......The truth is that the more 'real life' results i see on here, and the more attention i pay to keeping my own test conditions consistent , the more i realise that it's not like maths , 2+2 does not always = 4, I reckon you could test the same person at the same dose at the same hour every day for a week , and get a slightly different TSH and FT4 and FT3 each time.
Recently my TSH has gone up when it should have gone down, and fT4 has gone down when it should have gone up, and up when it should have gone down, and i'm only adjusting Levo without T3 to complicate the picture.
So i take bloods with a pinch of salt , and a view to the trends rather than the individual result.
And put it together with the known science and my symptoms, and accept that 2+2 might = somewhere between 3-5 on 3 times out of 4 .
But i promise you T3 does effect TSH.
I don’t disagree with you that T3 effects TSH and on some accounts it has a bigger effect on TSH than T4, but my results are all over the place and the link I’ve shared below shows sone interesting insights into how sensitive (or should that be over sensitive) TSH can be.
What we do also know is that low TSH is expected to reduce conversion of T4 to T3 and raising rT3 at the same time. So despite adding in T3 one could see a less marked increase in T3 than expected.
It’s a bit of a minefield this, but no different to someone working in the fields of Finance and Banking. Except in those fields they will go the extra mile to decipher the numbers whereas our arrogant and lazy Endos are too reluctant to delve deeper and come up with better answers hence the need for us to do our own research and analysis!
The canadian site you refer to is reliable and balanced in my opinion.Many other internet sources are not. Many endo's are not either.. and a lot of research is hopelessly blinkered in it's methods, and doesn't test all the necessary things often enough , like fT3.
The truest thing i've read on treating thyroid disease is that "it's more art than science"
The TSH only truly has a role to play as a feedback system to the body when the thyroid works. Once the thyroid stops working then what ever you put in re Replacement thyroid jormones will affect the tsh loop whether t3 or T4. However you are bypassing that loop because your thyroid isnt able to respond efficiently to the loop anymore hence the need for thyroid hormones. This is why blood test results for ft3 & ft 4 become far more important than the blood test result for TSH. Unfortunately the medical profession has become far too obsessed with the TSH......its a cheap way of testing and treatment by the TSH always leads to undertreatment but because doctors treat by TSH ranges which are very wide and dont take account of signs and symtoms they dont pick this up. Also blood tests do not pick up how much thyroid hormone is reaching the tissues......you can have a high level in your blood stream but if that isnt bring absorbed into your tisdues you will feel very ill.
Surely the only important thing is how you feel? During the time that I have been increasing my t3 and reducing t4, so that I no longer take the latter, my TSH jumped around. At one stage it went to 8 for no apparent reason and has now settled well below 1.
I’m fine with that becauseI feel great. And, when you think of it, why would you need something to stimulate your thyroid to produce t4 if your body can’t process it into t3? And you are taking enough t3 anyway?
Do you have a problem with a GP or endo who won’t give you t3 on a prescription?
I know what my advice would be, but I’m not an expert - only on myself.
Good luck
Amen to all of that.
You are treating your blood test results as if your body has no other aspects that would affect the results.....and then confusing yourself. In order to get the whole picture via blood tests you would have to test far far more than a thyroid panel because of the interplay between different hormones, minerals, vitamins never mind our immune systems, other conditions or toxicities at play.
This is why nedicine is as much an art as a science.......something the medical profession appears to have forgotten!
hi!Same w me... a little T3/cytomel has reduced my TSH to .01. Will your Dr allow your TSH to remain at that level as long as you feel well & t3 & t4 blood resulrs are within range.
Thx!
Best
He’s asked me to reduce T4 as my TSH is so low, let’s see how the next set of results goes.
He’s my 9th private Endo, and the only one who actually bothered to put me on T3 so I have to have done faith in him - all the others fobbed me off and told me I was fine/offered anti depressants/suggested I lose weight! Surprising that at £300 an appointment these people can be so lazy and incompetent!
Tried that! Now... trying reducing T3 again!Sadly... I felt the best ever despite TSH of .01 & blood levels both within range
He may have allowed you to have łiothyronine but he is then focusing on the TSH level. Was your ftfour in range? Sorry my keyboard is playing up..... And was your ftthree in range? These are the two levels to focus on. Your TSH will be supressed that is normal on combination thyroid replacement. Your specialist should know that. Lol.... My endo with many years of specialising in thyroid problems told me so long as your thyroid hormones are in range no harm can be done. He wrote to my GP stating that.
My TSH totally tanked after starting on T3 only. I don't take any other thyroid hormones. I was at 35 mcg and my TSH tested at .01! (Down from 2.4 prior to T3). My naturalpath doctor has me down to 20mcg, and I am eager to see what my next TSH level is.It's a known fact that T3 brings TSH down to nothing. All the doctors freak out about it. There is a risk of bone density diminishment after long-term use.
We are hoping I don't have to be on it long-term, and I am also taking Cal-Mag Citrate supplements with D3/K2 to hopefully mitigate the diminishment somewhat.
Taking almost any dose of T3 will suppress TSH for many, many people
Most important results are always Ft3, followed by Ft4
Thanks for the replies. Any credible research or other sources for these assertions?
If you search forum posts, you will find numerous references to this and other effects of T3 therapy. If you don't want to do that, have a look at the detailed and fully referenced blog posts by Prof Tania Smith at thyroidpatients.ca and Paul Robinson at paulrobinsonthyroid.com Or read some of the many books about the thyroid, search through papers on PubMed...
Excellent thanks. Couldn’t find anything on Google apart from contradictory posts with no back up. I’ll get onto those suggestions now.
Try Google Scholar rather than Google.
T3 has 3x as much effect on TSH as T4 onlinelibrary.wiley.com/doi... .
When that is true... does your Dr understand a lower TSH of .01/.03.... or does the Dr lower youe meds to raise the TSH?thxx
Adding T3 to T4 medications definitely makes a difference to your TSH. When I was on Levothyroxine alone for years my TSH never got below 4.0 (0.35-5.5). Now I’m on combined T4 plus T3 my TSH hovers around 1.00. It can go a little higher or even got suppressed on a couple of occasions. Since starting T3 about 18 months ago my thyroid bloods have been tested 16 times. 13 times my TSH in range and 3 times TSH slightly suppressed. The times it was suppressed my T4 blood was higher not over range but higher than the other 13 times. As soon as I slightly lowered my Levothyroxine dose from 75 a day to 60 a day my TSH came back in range and I felt better. I take liquid Levothyroxine so tailored doses are easy as you just draw your correct dose into the syringe. Also a lot will depend on your daily activity. If you don’t do much activity for days on end your T3 could build up. And the opposite if you start regular daily exercise. Its all about balancing your daily output with your daily input of medication for you individually. When I started the gym regularly 5 times a week I had to increase my T3 to three 5mcg doses a day rather than twice a day when not going the gym regularly. If my thyroid system worked normally your body just reacts and does what’s necessary but as I have a conversion disorder of T4 to T3 I need to gauge it myself. And no sudden increase or decrease of medication or you’ll feel it go too high or too low and get symptoms to alert you to that.
Adding T3 definitely causes your TSH to lower. But remember that ones TSH moves much slower than your T4 and T3 levels. T4 and T3 levels react quickly to adding medication whereas TSH reflects changes much slower. I know this for definite as I’ve had blood tests done close together within days, when my T4 and T3 levels have moved but my TSH had not at first only after say 5/7 days. It allows the odd burst of higher doses of T4 or T3 but alarms by going over after days of over dosing and same goes in reverse if you’ve lowered your dose for many days.
It’s all about balancing your activities and life style versus your thyroxine intake. If you went on a walking holiday you’d probably need more than a holiday just lying on a sun bed all day. So think about how active you’ve been between the last T4 test and this latest one. Have you done less as it’s winter now and not doing as much. I’m certainly not getting as much exercise as I was in the summer months.
I’d lower your T4 slightly for a week and see how you feel. As I mentioned in your previous post you can get the same feeling either over or under medicated.
Some really good points you raise, particularly around activity levels. I haven’t commenced any exercise yet, I was buzzing the first 2 weeks on T3 so was keen to exercise but the buzz has now gone somewhat and my muscles are really tight again so exercise will have to wait till we stabilise the thyroid dosing.
Main thing is for me to maintain a stable level of T4 and retest in 6 weeks then we shall see which direction we go in. I suspect it will be a small increase in T3 next time but let’s see.
I think you may well feel those symptoms of tight muscles and lack of buzz while your T4 is over medicated. There’s no need to have very high T4 levels when taking T3. Especially if you are a poor converter. T4 just sits and stacks up waiting to convert to T3 as we know. The more T3 you take the less T4 Levothyroxine will be required to convert, T4 will build up possibly switch on reverse T3 dumping it and your TSH will get suppressed alerting to reduce T4 levels. Your symptoms will remain and you’ll be fighting a losing battle.
Hi there, I've just been reading the article on thyroidpatients.ca about how T 3 suppresses TSH. I'm really concerned as my G.P is badgering me to take a blood test because , after complaining and quoting the 1.6 per kg dosing guidelines, they put my Levi up to 100 from 75. I didn't notice any difference in how I felt and now take half a 25 mg T3 tablet which I buy myself. This definitely gives me more energy but I do get a terrible energy cash in the afternoons. I worried that my T3 will have suppresses my TSH so much that the Doctor will panic and lower my Levo.... Can I stop taking the T 3 for a few days before the blood test to eliminate it's effect on TSH?? I hope you can help xxx
You don't have to take a blood test if you don't want to ... just tell your doctor you feel well and don't feel the need to have one. I do my own private blood tests and I certainly don't involve my doctor in my thyroid health. My GP goes by the TSH like most doctors and that is a pituitary gland hormone not a thyroid hormone and it will be low if you are taking T3.
Hi Lora, thanks for replying so quickly. I think I'll try that when they phone next time! So ironic that you can't get an appointment when you're ill but they are so on the ball about chasing you over TSH levels...maybe they're scared of being sued if TSH levels cause bone issues??? To be honest I haven't read up on the dangers of low TSH because feeling well enough to live my life in the present, while my children need me, has been my goal and not worrying about the future. Thanks again for responding x
You can listen to your doctors advice but it is entirely up to you whether or not you take it. I get a letter once a year asking me to come in to monitor my "condition" and I usually bin it because my doctor has no idea about thyroid disease and has actually said this to me several times.
Sad but true. If mine didn't even know how to calculate the starting dose... Says it all really! Definitely, going to ignore them and get bloods done by medichecks again myself..it's been about a year and it will be interesting to see my FreeT3 before I consider increasing my T3 myself( primarily because I crash in the afternoons and after exercise am exhausted the following day. ) Xx
It does sound like you might need an increase.
A supressed TSH level does not affect bone levels! This is a myth that has been peddled by the medical profession which they have never bern able to prove. Having too high levels of thyroid hormones for a sustained period can indeed cause harm eg affect your heart and bone levels. Equally being under treated can lead to all sorts of nasties including furring up of the heart, high blood pressure, increased colesterol levels....and so forth.
The trouble with GPs is that they have had no significant training in hypothyroidism so just go by what's on their screens......this amounts to dangerous meddling in my opinion & leaves many feeling really ill often for years. My GPs meddling left me on a cabinet of medicines when what I needed was appropiate treatment for hypothyroidism. All those additional meds disappeared once that happened but I had to seek help eslewhere to get proper treatment. I do wonder if this is the case with all chronic conditions as treatment for b12 deficiency or vitiligo was no better. These days I read up a lot before visiting a doctor to try and avoid the quackery.....lol.
Thank you so much for your reply. I' m definitely going to put off the GP blood test until the medichecks results are in and then make my own decisions on dosing( with a lot of help from all the lovely people who support each other on here!). If they do reduce the Levo and medichecks T3 and T4 results suggest otherwise, I'll have to buy T4 as well as T3. Getting vits done as well, although I have supplemented for over a year with ones recommend here so hopefully they will be at good levels. I will post my results as soon as I can and hopefully they'll give me the information necessary to begin to change dosing and feel better. Thank you again x
It may not be the T3 suppressing your TSH. If your T4 is over the range from the latest increase it could be that causing a TSH to lower. Really all three T3, T4 and TSH needs to be tested at same time. But if both T4 and T3 are over and TSH suppressed it will probably need lowering for both Levothyroxine and T3 medications. T3 has a half life in your system of 2/3 days also. If you’re buying your own T3 then they can’t stop you taking it really. I’d be very reluctant to stop T3 or T4 medications to satisfy a blood test. You’ll nose dive with symptoms and may take a while to stabilise again if you reintroduce it. I’m no Dr I just try to go on my own experiences, blood test and symptoms. It’s taken a good while for myself to work out what is best for me. What I do know is it’s all about your daily activities and how much you take and when. I take T3 twice daily but will increase to three times daily with 7hr intervals if I’m going the gym regularly and only if it’s for a prolonged period. Do you take your T3 periodically throughout the day. If your a poor converter, which I am, I need it throughout the day as it only lasts about 7/8hrs with 2/3 days half life. I sleep fine if I take my last dose about 8/9pm when exercising.
I’d get a private test done first snd see what that says before agreeing to get an NHS test done. Do you have Patient Access? I’d apply for this through your surgery if not. We are all entitled to this service. You can then check all your test results as they arrive in from the NHS lab.
Thank you for such a detailed and informative reply. I haven't had a blood test with the G.P for ages and they said it was 0.2 so I think the additional ,of 12.5 mg T3 will probably lowe ii to a level where they'll want to reduce the T4. I haven't told them I'm taking T3 but have decided to do my own medichecks test (haven't done one for a year) and then decide what to do with T3 dose. I think that like you I need to take multiple doses as I crash very badly after about 6 hours after taking T3 . Also if I do a hike(6 miles plus) I'm completely exhausted for the whole of the next day. So this is my plan.... Get medichecks test, see how far through range T3 is and if room to go higher add another 12.5 T3 early afternoon. If T4 is too high then I will reduce back to 75 but I can't imagine it will be as I weigh 75 kg and so 100 plus is the starting dose for my weight . I'm gluten free, take all recommend vits on here and exercise by dog walking around 4 milles a day. It would be great if you could comment on my plan. 🙂Thank you
Because the blood test they want is following an increase in dose (and especially because the suggestion came from you not them) i think you may well find that they will not be happy to continue to prescribe at that level unless you do have a test, at some point , (although you might be able to put it off for a while due to covid)
What were you results before the increase to 100mcg ? how close was fT4 to the top of the range if they test that?, and how low was TSH ?
If you test and fT4 is still within range, then you have a good argument to continue , but if it's gone over it may be harder to convince them. Same issue applies if TSH has fallen too far for their comfort .
The prescribing GP is responsible for the risks of the medications he prescribes , so it is reasonable that they want to monitor the results. And rightly or wrongly they do believe that a very low TSH comes with risks for heart and bone health. So it is not realistic to just expect that they will continue to prescribe 100mcg if you refuse a blood test.
You've also added half a 25mcg of T3 so your results will show that , probably by reducing TSH further than the levo increase alone would have done.
They are unlikely to notice the raise in T3 cos they hardly ever test it.
There is no way to know for certain how long you would need to stay off the T3 for TSH to come back up to the level that is related to just the Levo increase, but it would probably be quite a bit longer than 'a few days', and in fact if it has gone really low it could take months, or not come back up much at all no matter how long you waited.
(The reason for the 6 week delay in testing after a dose change is because of how long it can take TSH to respond)
Stopping T3 for say a couple of weeks, for a blood test, might or might not raise your TSH , and would certainly upset your body while it tried to adjust to the sudden change from something it had got used to, so probably the experiment would leave you feeling rough for several weeks.
So whatever you do it is probable that you will need to get a good enough understanding of the risks of low TSH as they see them, in order to persuade them to continue to prescribe 100mcg.
I can find you some old posts discussing the subject if you need.
One further thought, before increasing the T3 dose , might it be wise to try splitting what you already take into morning and afternoon ?
You do know Levo is cheap as chips to buy online? My GP refused to give it to me even though I had an exemption card and had taken it before. I then went home and suffered for about 18 months before a kind lady on another site showed me where to buy Thyroid S online. My GP would not help because my TSH was within range even though my T4 and T3 were very low. I had no choice because I was fighting for a quality of life and I have no intention of ever involving my doctor in anything to do with my thyroid health now. Even last year when I was admitted to hospital with a suspected thyroid storm the hospital only tested my TSH. I then went to see my GP with a letter from the hospital and he did ask for a full thyroid function test but the labs saw my TSH was in range and refused to test either the T4 and T3. I now only see my doctor if I really need to. I and my husband both worked for the NHS for many years and we have both lost confidence in the service now.
Have you considered trying another GP? I’ve changed GP a few times over last 10 years (due to moving home) and no one has questioned my need for T4. I have regular blood tests at my GP which show I’m within the reference range but that’s no reason to discontinue treatment.
I’m not a fan of GPs or the NHS, the people who work in it are generally brilliant but they are so overworked and underpaid. GPs especially have the unenviable task of managing budgets whilst being generalists, when sadly most people with chronic conditions need a specialist. We need better funding of the NHS but successive governments have not increased funding whilst the population grows and grows older.
I live in a semi rural area and I cannot try anyone else. I am a Graves' disease sufferer so at the moment I am remission so ok at the moment. There is no one who can help me in the UK because all they suggest is RAI or to have my thyroid removed and I would then be in a worse position than I already am if I did that. I have gained enough knowledge from sites like this one and the US to self treat if I need to and really don't want a GP to interfere in my thyroid health. Thanks for your reply.
Hi Lora, I've just written a long reply to Tattyboggle and hopefully to you( I'm not sure how these conversations work!) But in case you didn't see it I just wanted to thank you again and say that I will be following your advice and Tattyboggle's to hopefully start to feel well...The G.P has had 2 years to help me and it hasn't worked so if they do take the T4 off me I'll just buy it and continue to experiment with T3 and T4 myself. I'll post as soon as I get my medicheck results...P.s I LOVE your profile pic x
Yes i did know that, thanks 
i know people who don't need/want a prescription can happily ignore the GP's request for blood's, but if you want the NHS to prescribe/acknowledge the condition, you have to jump through the hoops to some degree. Was just pointing this out because you reply gave the impression that HoovyPudsey could ignore the requests and still keep the prescription going.
I actually think my GP surgery thinks I am still taking Levothyroxine because they put in my annual letter that I need to have my medication checked lol That is how useless they are .... then I get another letter saying I have a mental health condition! I feel sorry for people who don't know the NHS as well as I do and just do exactly what their GP tells them to do.
Hi there, thank you so much for taking the time to write such a detailed response. I agree that they will want a test eventually and I will submit eventually but I do buy T4 online as an emergency stock if my repeat prescription s are late, so I will be able to buy my own if they decide to take if off me. When on 75mg T4 my TSH was 2.8 so not that low and T3 only 43% through range with T4 15,% through range so again way too low and I didn't feel better than before I had any meds!
So I've just purchased the full thyroid tests from medichecks and am anxious to see what the new levels are. (Got to arrange a blood draw so will be a delay) I think I will try splitting the 12.5 into 2 doses to try and avert the afternoon crash and then wait to see what the results are from medichecks.... I'm hoping that there is room for more medication ie that the T4 and T3 are still not high enough in range because I really don't feel well...usual symptoms.I have read that T3 and T4 should be 75%through range to feel really well.
So My new plan is a hybrid of both your advice ladies. Thank you so very much Lora7 and tattyboggle, for taking th e time to help me x
Surely, if your muscles are tight, you need to exercise to make them work better? If you stop leading a normal life, I believe you can end up in a vicious circle and spend your life studying every minute detail of what your body is or isn’t doing. That can’t be a good thing because I believe it makes us even more paranoid and hypercondrical.
Having been ill for so long, I know how easy it is to let that happen. Despair can be so overwhelming, but at least you’ve found such a helpful site that can give you hope for the future.
Personally, I wouldn’t read too much, that can also make you too introspective. Just go out and battle the useless doctors and fight for your future. Even if it means self-medicating by buying t3 from abroad.
Good luck!
Well... this hasn’t been entirely my experience and I say this having spent nearly 6 months in the gym until put into tier 4!
What exercise does do is crash my fragile T3. On the plus side, it eases the tight muscles for about an hour on a good day and then the stiffness returns... the stiffness is at root, a hypo / medication problem for me I believe - which isn’t to say exercise doesn’t help a little - but six months with a PT tells me that it doesn’t solve it entirely either.
Agree on that, I have reduced my T4 over the last week so keeping that stable now. I’m down from 150mcg to 133mcg per day (taking 150, 150, 100) so hopefully that puts me in the right direction.
T3 is the predominant inhibitor of TSH secretion.
ncbi.nlm.nih.gov/books/NBK4...
If you also happen to have elevated levels of cortisol, your TSH will be affected (lowered) by this.
FT3 influences the activity of all the internal organs of the body including the thyroid
High TSH on T3 & NDT
Suppressed TSH advice 
High TSH
Decreasing TSH while on T4/T3 combo
