Thyroid UK
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Do I need Reverse T3 Test?

I've been unwell for quite a while now and my GP will only test for TSH so I have decided to go privately and have other Thyroid tests done. So I'm going to have




Thyroid Peroxidase Antibodies

and Thyroglobulin Antibodies. Can anyone tell me if it's very important to pay quite a bit more and get Reverse T3 included? I don't know what this is! Thanks

7 Replies

My view is that rT3 assays are a waste of money.  Noone knows what a particular value means.  rT3 blocks the action of T3, but how does a total rT3 figure relate to free T3?  What are their relative binding affinities?  How much rT3 is staturating the receptors compared to T3?  I've never seen any answers to these questions, so can't see how you can interpret the result other than to say it is higher or lower than usual.

If you fT4 is high your rT3 will increase, if you have a degree of central hypothyroidism (low TSH for given fT3, fT4) again your rT3 will increase.  If you are on a very strict diet or depressed your rT3 will increase.  You can work all this out without paying for an rT3 assay.  If you get one your doctors will (quite reasonably) ignore it.

There are suggestions about how to interpret rT3 figures, ratios etc but these usually come from the company marketing the test.  I'd save you money.  This is just my opinion.


briskate... You might check out this website for information on R T 3 and then make up your mind about whether or not to test R T 3.

I have been on NDT for twenty years and have never had a RT3 test but..... I have never had a problem and have felt great on NDT.  The only time I had horrible hypo symptoms was when I was in Synthroid for a year after diagnosis and before I switched to NDT. 

So, do you HAVE to have a RT3 test done?  Of course not.  But it is of value when you are checking things off and are still having problems or unresolved hypo symptoms.


I had mine tested, all through Genova. I thought it worthwhile to get a complete picture. I also did a urine test for the thyroid hormones. 


But did the rT3 give you any useful information that helped with your treatment?


Hmm, I had a result of 20, the range was 10 - 24.  I guess it was just part of the whole jigsaw.  It will be interesting to do it again in future to see how it has changed with having treatment (self meds).  I am a person who likes to see all of the picture though.  I can see that it is in range. although on the higher end and if do again in couple of months time, I can see how the Thiroyd is having a result and if conversion is worse.  Then I can change my supplements accordingly.

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Well, let us know how that works out. :)


Thanks for all your replies. Much appreciated. I am new to this and don't know if I have any thyroid problems yet - just wanted to know if the reverse T3 is needed for a very first test or later down the line if something wasn't right. Thanks for your help everyone :)


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