This might seem obvious to the experts on here, but if you are on T3 only, doesn't your T4 level drop through the floor?
I'm currently taking 2 grains of NDT and between 10 - 15 mcg of T3. My endo was concerned recently because my blood T4 was on the low side although the T3 was in the upper range, and so wanted me to increase the NDT and lower the T3 (her actual words were that she wanted to "wean me off" the T3!). Now, I'm not averse to that since I have recently read about the common mistakes when taking NDT [thanks, Shaws] but at the moment I am not entirely convinced that my body likes T4 anymore (long, long story), so if the increase in NDT doesn't stop the arrhythmia and I don't feel better, I will be wanting to try the T3 only protocol.
Thus my question, if my endo was a bit concerned about the low levels of T4 recently, will she have cause to freak if I'm on T3 only? As in, won't the T4 levels drop away altogether?
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Schenks
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Yes, and your tsh may be nil. You and I know that this can be expected when using t3 but whether or not you can get your doc on board is a different thing.
Dr. Lowe: I respectfully disagree with your endocrinologist. Studies indicate that T4 is of no use to anyone except, figuratively, as a storage unit for the metabolically-active thyroid hormones T3, T2, and possibly T1. When T4 ends its long ride through the circulating blood, it enters cells. There, enzymes convert it to T3, and, after a while, other enzymes convert T3 to T2. The T2 becomes T1, and eventually T1 becomes T0 (T-zero). T0 is just the amino acid backbone(called "tyrosine") with no iodine atoms attached. Because it has no attached iodine atoms, T0 is no more a hormone than is T4.
Rather than being a hormone, T4 is a “prohormone.” That means that enzymes have to convert T4 to T3 before T4 benefits us. T4 is no more a hormone than beans in an unopened can are a food. For all practical purposes, canned beans become food only when a can opener frees them so you can eat them. Hence, T4, like canned beans, only potentially benefits us, but actually does so only after being freed from its metabolically unusable form.
I respectfully disagree that T4 is useless. If someone is on T3 only, then the dose really needs to be titrated much more carefully than if someone is on T4/T3 or NDT/T3. At least when there is some T4 floating around, if excess T3 is ingested, then the body has an option to create a bit of rT3 to counteract excess.
If T4 were useless, our thyroids under normal circumstances wouldn't make any in the first place.
Also having T4 stored in tissues, is a safety issue in case a person suddenly has no access to T3.
I believe we are talking figuratively here about synthetic T4. As Dr Lowe prescribed either NDT (containing all necessary hormones) and/or T3 for his patients, I believe he is reassuring this patient for whom T4 did nothing for her and to get well has to use T3 only like many of us have to. If we take levothyroxine alone and are not benefiting from it in any way - we have to have an option otherwise we remain very unwell.
Given that you still have some functioning thyroid gland, Schenks, your T4 won't disappear, although if you switch to T3 only you're liable to suppress your TSH and thus T4 production of course. I don't know enough to comment on your arrythmia, other than to relate my own experience that all my symptoms cleared up once I'd reached a large enough dose of T3, but as I'm TT, I may react differently to you. I wouldn't worry too much about ingesting too much T3 - I take 80mcg in one go and my Serum Free T3 is 4.8pmol/L range (3.9 - 6.8) so I must be regulating OK without the mechanism of rT3. I also find that I can forget a dose without going hypo (I suspect it's stored in the liver, mainly). I feel a lot of the anecdotal stories of swings in and out of hypo/per with T3 are down to simply not taking enough in the first place. Regards Richard.
Thanks to all. Shaws - I hadn't caught on that Dr Lowe prescribed NDT and T3 - that's reassuring since my endo wants me to wean off T3 fro some reason - she still hasn't told me why. But the info about raising NDT every fortnight and giving it a chance to work is what prompted me to take the 1/2 grain this afternoon and leave off the T3 - although I have just realised I should have taken 5 mcg of T3 alongside until I increase the NDT by half again!
Richard - what is TT? Is it perhaps total thyroidectomy? Mine was a partial, but god knows what is left. I have increased the NDT today from 2 grains to 2 1/2, but the arrhythmia/ectopic beats have come on something fierce. I have been taking 10 mcg of T3 in the afternoon with the frequent addition of 5 mcg in the evening when the arrhythmia starts up again - and I've just realised as above that I've blooming well taken too little of the T3 all in all. am about to take another 5 mcg. And others on the site take their T3 in one go - if this bl**y increase in NDT doesn't work, I'm going to use the T3 protocol only. I guess I should know by the time I am up to 3 grains. If no improvement of all my symptoms, I will be changing over.
Yes TT is total thyroidectomy (1982, cancer). I was fine on T4 for years, then it gradually stopped working, but in a subtle way so that I thought I was just getting old and knackered a bit sooner than I'd hoped. Of course it took me ages to work out what was happening, 5 endos til I found one that would risk T3, and then 2 further years to get rid of the effects of the T4, which had pretty much dismantled me by then. I've been on T3 only for about a year now, so the sums above will add up as I reckon I can still feel much better! I'm only mentioning all this as I wonder if you've had a similar experience, with Levothyroxine working well for some years, then gradually failing?
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