Transitioning from T3 to T4

Prior to taking Cytomel my tsh was 2.1, ft4 was 1.0, and ft3 was 2.5.

After a month and a half on Cytomel 18.5mg my ft4 was .7 (.8-1.8) ft3 was 2.5 (2.3-4.2) and tsh 1.3. I did not take my medication for 24 hours prior to testing. It appears that adding 18.5mg's of only t3 has not increased my ft3 level at all, and it's brought down my ft4 levels and tsh.

Needless to say, I felt like even more crap than I did to begin with after taking t3 only. Instead of adding more t3, I decided to try 50mcg of Levo, while slowly reducing my cytomel so I don't have too many terrible hypo symptoms as I transition.

So for the last 3 weeks, I have been on Cytomel 12.5mg (down from 18.5mg) and 50mcg of Levo. My question is, can I expect my ft4 levels to reach at least the 1.0+ range on this dose of Levo? The Cytomel wasn't even helping with my ft3 level at 18.5mg's so at 12.5, I suspect it is helping even less. And as I continue to gradually reduce the Cytomel as the t4 builds up in my system, I am hoping to see my ft4 and ft3 rise, provided I am able to convert. Which I am pretty sure I can convert. Doc put me on t3 only first to help with the depression symptoms as well as low thyroid. I wish now I'd just started on t4 and seen how well I convert.

Does this sound like a pretty good plan? over the past three weeks I have definitely felt better, so I know I must be able to convert.

Also, as I asked before, can I expect my ft4 levels to reach at least the 1.0+ range on 50mcg of Levo? And is the 50mcg Levo likely to surpress my tsh below .5?

4 Replies
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I am confused. You say you switched to 18.5mg of T3 which I assume is equal to approx 75mcg of levo which is quite a low starting dose to provide much effect and should have been increased every 2 weeks by a very small amount until you had relief of symptoms.

Maybe if you had started with 25mcg of T3 and then after a couple of weeks increased by 1/4 tablet and so on until you felt better. I am not medically qualified but take T3 only myself.

Your dose of T3 was too low to raise your T3 levels and taking T3 only lowers any T4 which you had in your body because you were on T3 only.

We can switch from one thyroid hormone product quite easily. Just stop one and take an equivalent dose of the next choice.

50mcg of T4 is a starting dose and I doubt it would suppress your TSH.

Taking T3 would lower your FT4 and TSH, that's normal. But, your FT3 only appears not to have risen because you left it off too long. You should only leave 12 hours between your last dose of T3 and the blood draw. So, your normal circulating level of T3 is actually higher than that.

But, in any case, 18.5 mcg is such a tiny dose, it's really not likely to make any difference to the way you feel. If taking T3 only people need much higher doses than that. It wasn't the T3 itself at fault, just that you weren't taking enough of it.

Does your plan sound like a good one? Only time will tell. But most people would give their eye teeth to get T3 prescribed, and hearing of you throwing that away, really won't seem like a good plan to them! I cannot imagine why you want to be on T4 only. Why not just add in some T4 to your tiny dose of T3. Then, if your conversion is reasonable, both your T4 and T3 will rise - if your conversion is bad, your T4 will rise and T3 get even worse. And, I cannot imagine your body is going to be happy, after having been on T3 only, to have it completely removed. And, the low FT4 when you were on T3 only, wasn't what was making you feel bad, it really doesn't matter much, if it's low, as long as you're taking enough T3.

Eshep

Absolutely agree with Greygoose :

Taking T3 would lower your FT4 and TSH, that's normal. But, your FT3 only appears not to have risen because you left it off too long. You should only leave 12 hours between your last dose of T3 and the blood draw. So, your normal circulating level of T3 is actually higher than that.

My conversion is poor, but I do convert to a certain extent. I take a Levo plus T3 combo (my T3 is self sourced and self medicated). Many tweaks over a year or so has taught me that I need a certain amount of Levo to keep my FT4 at a certain level, too low and I get dreadful fatigue, and I need a high in range FT3. You just need to keep tweaking to find your best levels. But when testing, leave 24 hours between last dose of Levo and blood draw, and 12 hours for T3. Do it every time and you can compare accurately.

Thanks for your responses.

I am still taking the low dose t3, but adding the Levo 50 has made all the difference. I feel about 80 times better. So I must be converting some t4 to t3. We shall see at my next blood draw.

If I only take my t3 once a day, in the morning (8:00Am), I really don't have an option for getting blood taken at the 12 hour mark. Any further suggestions?

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