Thyroid UK
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RT3 help

Whilst I'm sitting around Inam trying to educate myself about RT3 this was on the 7th July this year.

Blue H blood test before I started taking T3 is

RT3 23.0 10 -24

Reverse RT3 ratio L 10.28 >20

At this time I was on 75mg T4 levo and as instructed 100mg on the weekend

I did sometimes not increase on weekend depending on how things felt

I have since gradually introducedT3 about a week or so later.

My doc said he would test this at 6 weeks

That saw my FT4 lower 13.8 (12.0 - 22.0)

F T3 4.6 (3.1 - 6.8)

Previous time 7th July FT4 19.14 Same ratio

FT3 3.63 Ditto

Having pushed the T4 down lower does that give me a better chance of RT3 problem

I trying hard to get sorted and have a better understanding of having no thyroid .

The help is very poor from doctors this site is a life saver to me and I am very grateful for your input.

I am a bit scared of the thought of being on T 3 (as a possiblity) only because of the implications when needing NHS help in future . Or getting my supply which is working very well presently. Sorry to be a pain to all you good people 😔 But thanks x

4 Replies

The FT4 goes down, because your body does not need to hang on to so much for conversion. So, that reduces your risk of converting to rT3. It's usually too much T4 that gets converted to rT3.


I think there's a mistaken notion about Reverse T3. This is an excerpt from a Dr who was an Adviser to Thyroiduk. He was also a scientist and a researcher who himself had Thyroid Hormone Resistance. Go to the date March 24, 1999 on the following link and this is an excerpt:

A popular belief nowadays (proposed by Dr. Dennis Wilson) has not been proven to be true, and much scientific evidence tips the scales in the "false" direction with regard to this idea. The belief is that the process involving impaired T4 to T3 conversion—with increases in reverse-T3—becomes stuck. The "stuck" conversion is supposed to cause chronic low T3 levels and chronically slowed metabolism. Some have speculated that the elevated reverse-T3 is the culprit, continually blocking the conversion of T4 to T3 as a competitive substrate for the 5’-deiodinase enzyme. However, this belief is contradicted by studies of the dynamics of T4 to T3 conversion and T4 to reverse-T3 conversion. Laboratory studies have shown that when factors such as increased cortisol levels cause a decrease in T4 to T3 conversion and an increase in T4 to reverse-T3 conversion, the shift in the percentages of T3 and reverse-T3 produced is only temporary.


Also, if impaired conversion was the source of the problem in my fibromyalgia patients, they would respond to a normal physiologic dosage of T3. However, most euthyroid fibromyalgia patients require far more than normal physiologic dosages to overcome their thyroid hormone resistance.

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Still not quite there yet ,as on the report it give >20 as the norm for Reverse T3 ratio.

So unclear with those two answers which seem to say the opposite🤔

As stated it had been the Reverse T3 that was high which was at the very top of the range 🤔 Thought that was not good.

Sorry I'm being thick but if I can get my head around this maybe it will be better for me to understand


Just add to that is a good reason for me to reduce the T4 in my case and increase the T3??


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