why does t3 decrease t4 levels and can this effect symptoms.

[samking5]

hi peeps

I made a post recently but I wanted to see if anyone had any deeper knowledge on this topic.

So before starting t3 meds I had a test of TSH 10 FT4 18.1 (12-22) FT3 5.1 (3-6.8)

after 4 weeks on t3 meds I started feeling kind of weird and was worried I was overmedicated (first 2 weeks 2.5 morning only second 2 weeks added afternoon 2.5 dose).

*LATEST RESULTS: I went for an afternoon test results were TSH 6.2 FT4 18.4 (12-22) FT4 5.6 (4-6.8) So defo not overmedicated at least on the FT4 side.

Now of course the FT4 level is actually higher, however since it is afternoon test, going of my past results it is probably elevated around 2-3 points above the pre medication test. This means that my FT4 levels have in fact dropped and are probably around 15-16 pre med - This is too low for me!

is the T3-induced decrease of T4 levels due to some kind of absorption competition, would taking it at a different time fix this, or is it due to something with the d3 enzyme blocking or converting T4 to RT3 at a higher rate?

The thing is I did not react badly to the T3 the first few weeks, in fact I felt it was helping!

symptoms I am feelingnow : muscle pain, fatigue, brain fog (only have this when im pretty low or overmedicated) some palpitations but no tremors with a lowish heart rate and palpitations. when hyper I always have tremors + going off results I do not think it is that.

perhaps I need a higher dose of levo to tolerate t3 over the long term if its going to decrease FT4 - I just never felt really good on levo, always felt delayed recovery, like the hormone was not getting in there fast enough. the first 2-3 weeks on t3 my recovery felt better.

The only way on levo I could get into range (1-2 tsh) was to increase FT4 levels well above range which made me overmedicated, perhaps with a touch of T3 I could be in range without too high FT4?

Gahhh its so complex!

[Hidden]

Hi

Do you have your latest blood results to share?

[samking5 in reply to Hidden]

I noted them on the post they are the second lot. The point is since starting t3 my ft4 levels have dropped even though i am taking the same 100mcg levo, I was feeling ok on the levo as long as i didnt push crazy hard, felt I think better as I started to introduce t3, but now worse and I think it could be because my ft4 levels have dropped off a lot. unsure what to do...

If I stopped t3 would ft4 levels go back to where they were? before starting I didnt know t3 meds would decrease t4 levels and I still dont know why.

[Hidden in reply to samking5]

You haven’t included the ranges for FT4 but at 18.4, they’re definitely high. I don’t know what they were before but it’s not unusual for FT4 to drop when T3 is added.

The most striking things about your blood results are the high TSH which suggests undermedication and the differential between your FT4 and FT3 which is indicative of poor conversion. Your T4 is not converting to T3.

It looks as though you need to decrease Levo and increase T3 a little. You say that you have always had to have a high FT4 to keep bloods in range. In a situation like yours, this would be a likely explanation.

What doses of Levo and T3 are you taking?

I’ve been in a similar situation. Increasing FT4 with a large dose of Levo is not the answer. You’ve made a good move by introducing T3 but you have some way to go.

[samking5 in reply to Hidden]

sorry ft4 range on that test also 12-22

I actaully I think it may be the other way around, taking 100mcg levo 5mcg t3 but my FT4 level was higher on levo only, so im wondering if I actually need to add some levo since the t3 meds appear to have decreased my ft4 levels.

My previous problem on levo only was it would take large amounts of ft4 to bring my TSH into range making my FT4 too high meanwhile ft3 wouldnt increase at all. So I thought a combination may work. that may well still be true, but I didnt forsee this decrease in ft4 levels which im not thinking may be making me feel bad.

If t3 is going to decrese my ft4 levels perhaps, I need to increase my ft4 levels to counteract this. perhaps then I can arrive at a TSh in range with a more balanced amount of FT4 and FT3?

[Hidden in reply to samking5]

You definitely don’t need to increase Levo / FT4. A higher dose of T3 will lower TSH which is what you’re aiming for. Your FT4 is clearly not converting. It’s normal for it to decrease when T3 is added.

My view is that that small dose of T3 should be increased. Don’t worry about decreasing Levo but similarly don’t be concerned if / when it drops when T3 is increased.

[samking5 in reply to Hidden]

hi ok but the ft4 levels are not high as I said it was an afternoon dose post meds which I know is not ideal but probably before meds they were around 16 which is low for me.

High for me would be 20-22 pre medication 23+ post medication (on 12-22 scale) .

My conversion I think is not terrible however It never kept up with my body and I could feel it.

Do you know why it decreases? ive seen a few people here state it does I havnt found out why.

just feeling very suprised by this sudden crash and looking for reason why, and I was also suprised to see those ft4 levels at that range.

[Hidden]

healthunlocked.com/thyroidu...

An old thread discussing the question which you’re asking. Posted it because there are some interesting responses.

There are various suggestions about why adding T3 lowers FT4. It’s thought that T3 increases conversion of FT4 to FT3 but a good idea to read the whole thread

[arTistapple]

The answers to this question need better clarification. I can see people are trying to help but the answers still seem undefined to me. OK I admit I am missing something here but my experience is similar to yours (although I have been on the forum a year longer than yourself) immediately feeling better with T3 but then it not lasting.

I had a very bad encounter with an NHS endo (by letter not an appointment) which involved over medicating on Levo and raising my T4 to way over what it should be. I was very ill after that for a while. My comprehension probably came to a bit of a standstill after that!

I understand the words - T3 reduces the T4 levels in the blood. However it seems I really don’t understand! I have introduced T3 (due to poor conversion) I think at least three times without success. It’s only this last time that this particular issue seems to have been brought to my attention as the cause of it not being truly effective. I have checked my posts and notes but I don’t think my lack of success was explained in this way before - that I was actually making myself more hypothyroid!! If this was explained I admit freely, it’s gone right over my head!

Previously I thought it was just an observation. “Introducing T3 automatically reduces T4 levels in the blood”. I did not pick up that it had an actual effect on the person - only the results! Like a purely aside observation. Silly me! Like you, I immediately felt the benefit but fairly quickly I started getting symptoms I associated with over medication (severe palpitations). With the knowledge above - introducing T3 lowers T4 and in fact can make you (me) more hypothyroid rather than less.

The same question was broached by someone I think was a lot more experienced than me around the same time I was experiencing this. Unfortunately they disappeared from the forum sharpish without a comprehensible answer (in my opinion) being reached.

I think we need some clear guidance and references to reading on this one. Apologies if I have missed this and someone has already made this explanation available but I need it too.

In the meantime I have returned to my previous dose of levo 100mcg very disappointed, losing heart and return of the usual hypo symptoms I have become accustomed to; rather than the very dramatic symptoms of my younger years (severe palpitations recently brought on again by the T3) - for which I am very grateful, but I would still like to get better than just existing.

[Mednews4 in reply to arTistapple]

just reading this post. Was there ever any resolution or updates on this thread. Experiencing similar symptoms with recent introduction of T3 - 3 weeks in. Shortness of breath, increase of heart rate 115/85 and usually a 90-10@/70ish. Feel this mainly after eating.

[arTistapple in reply to Mednews4]

I will undertake an answer here as it’s clear in fact this post was never resolved and now the person who was doing all the answering has disappeared too. Is this some sort of co-incidence ? I have noticed its happened before when this question comes up.

I was just sitting discussing this with my husband moments ago, because I am seeing an endo next week and one of my biggest questions is “After feeling ok, even very, well after commencing T3, why am I getting very undesirable symptoms after a few weeks?”

Recently I made a connection myself which could be important for myself but it’s very theoretical. For me it could be a blood sugar reaction because of the uptic in metabolism needs (not eating enough or appropriately - I am hopeless at organising food although I generally eat well) OR what we often see referred to is an adrenal issue. T3 and adrenals work in some sort of symbiosis, so continued adrenal support seems to be necessary so T3 treatment can be properly established.

It’s a complete pain to sort out for those of us it effects, because T3 does come over as the magic bullet. It’s extra disheartening when it doesn’t work for us, whatever blooming reason.

Maybe either someone comes along with a lot more wisdom OR can I suggest you start a new post?

[Mednews4 in reply to arTistapple]

thank you. Yes I started a new post this am.

[arTistapple in reply to Mednews4]

OK will check it out. Thank you.