Thyroid UK
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High RT3

Hi, I had a blood test back in Jan which showed high T3 and ReverseT3.

T3 3.1 – 6.8 (7.27)

Reverse T3 10-24 (33.0)

I was taking 3 grains of NDT and was displaying a couple of signs of being over medicated. Thought I’d drop down to 2¼ grains hoping that my levels would drop and was OK for a couple of months but things still not quite right.

3 weeks ago thought I’d try and do something positive to lower my RT3 level by reducing my NDT to 1 grain and introduce some T3, started on half a 25mcg tab for 2 weeks then felt the need for more and moved up to 1 tab T3 and now on 1¼ tabs. Still feeling tired by midday and some constipation. Had some bloods done 2 weeks ago which showed my T3 at 4.87.

I plan to keep to this for 12 weeks in the hope the RT3 will flush from my system. Does this sound like this regime should work? Will I still need to increase my T3 over the next few weeks?? And if it does clear my high RT3 what regime would I go back onto in order not to get high RT3 again???

Many thanks in advance.


3 Replies

Hi ColinK, I think you probably don't have any replies because I don't think much is known about rT3. I'll tell you the few things I know :p

For one thing, your initial freeT3 test (I'm assuming its freeT3 total T3 may work a little different) is too high, and this is the best indicator of whether you're on too much replacement medication. Ideally you want the number to be in the top third, but not over.

High freeT3 seems to be very much associated with high rT3. Theoretically it's a way for your body to mitigate having too much T3 delivered,as the rT3 blocks the over high T3. But also, rT3 can only be made out of T4, not existing T3. But I think it can also give you what works out as a misleading my high freeT3 result, if you've got rT3 hanging about, but actually little active T3.

You don't mention your TSH or freeT4 result, so it's harder to pin down what the overall situation might be.

The only treatment I've heard people really try for rT3 is to cut out all T4. I believe Clutter tried this route and went without medication at all for several weeks. I've done something similar myself, but I didn't really plan it correctly and ended up only going 3 weeks, which isn't long enough to flush all the T4. I think how willing you are to try something like this will depend how ill you are to begin with. C and I were both mostly bed bound when we tried it, so being in bed for two reasons doesn't make too much difference.

If you're fairly functional and working you probably want something less traumatic. It sounds like you have access to T3-only, so you could try that for several weeks. The half-life of T4 is about 6 days, so to really really flush it you want 10 half lives, or 60 days off.

Your final question of how to avoid this happening, number one that applies to everyone is to not take too much T4 or be over medicated in general. All the others I think are more specific and depend on your circumstances. RT3 is mainly made inappropriately when people are sick or over stressed, so if you've been hypo or hyper for a while, or had an operation or serious illness that led up to this, that could be an explanation. Adrenal/cortisol problems might also explain, or vitamin deficiencies - so those are the same things to look out for as any thyroid problem.

I hopesome of this helps and you get to the bottom of it!


That was impressive! There's so much to know! I'm glad I read it, I understand a bit better now :)


Haha, thank you Pastille! I was a bit concerned I'd ended up being clear as mud ;)

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