Low T3 free RT3 ratio

Hi, I'm new on this site. :) I have just about every hypothyroid symptom there is. My GP tested me last year and but results were normal. Symptoms have been getting progressively worse over the last 6 months so opted to have a private test which included reverse t3. My normal thyroid hormones are ok but my Ft3 and RT3 ratio is low 12.92. The report suggests that this could be the cause of the thyroid symptoms I've been getting but says that it can be difficult to get it treated through conventional channels. I have a GP appointment tomorrow and would like to be better prepared for it as find this all so confusing. Can anyone tell me what the right sort of medication would be to treat this if its not the normal meds? Has anyone else had this and been medicated and is feeling better? Any information at all would be really appreciated.

18 Replies

  • Welcome to the forum, Boojii.

    It will help members advise if you post your TSH, FT4, FT3 and rT3 results along with their respective ranges (the figures in brackets after results).

  • No problem, thanks for the tip Clutter.

    My results were:

    TSH 0.973 (0.270-4.200)

    Free Thyroxine 14.75 (12.000-22.000)

    T4 78.2 (59.000-154.000)

    Free T3 3.97 (3.100-6.800)

    RT3 20 (10.000-75.000)

    RT3 Ratio 12.92 (15.010 - 75.000)

  • Boojii,

    Results appear to be euthyroid. What thyroid medication are you taking?

  • I just had to look up euthyroid, meaning normal thyroid? I'm not on any medication as haven't been diagnosed with a thyroid problem by my GP. The commentary on the private thyroid test result came saying that my ft3 and rt3 ratio was low (normal ratio is meant to be above 20 whilst mine is 12.92) which may be causing my symptoms. Is this something your'e familiar with?

  • Boojii,

    Yes, euthyroid = normal. Your TSH is low-normal and your FT4 and FT3 are within normal range so you don't appear to have thyroid dysfunction.

    Most sites commenting that thyroid levels should be at certain ratios are usually referring to patients on Levothyroxine or NDT replacement therapy.

    Were thyroid antibodies and any vitamins and minerals tested?

  • Yes I had the whole lot done. Everything else was normal. Apart from Vit b12 - 676 (191/663) was high despite me being a veggie and not supplementing so not sure what's going on there! Vit d was 58 (50-200). I've started supplementing with Vit d because its right at the lower end of normal range to see if that helps.

    I have read that having a low ratio of F3 to rT3 can cause hypothyroidism despite all other normal thyroid tests being normal. It appears to be an underdiagnosed condition that not many GP's recognise due to limited research. Have you not come across this Clutter?

  • Boojii,

    I've not come across information that low FT3:rT3 causes hypothyroidism.

    B12 676 isn't high. Yours is a peculiarly low range, most top off at around 900-1100 with some topping off around 2000. You can't obtain B12 from plant foods so it would be sensible to supplement 1,000mcg methylcobalamin.

    VitD is optimal around 100 so it's a good idea to supplement Oct-Apr when ultraviolet light is too low to stimulate natural vitamin D.

  • Thanks Clutter, maybe the lab where I was tested has different ranges. It was the GP that commented on the report that said it was high. I can't imagine how it could be though and as you say might be worth me supplementing anyway.

  • You must be getting pretty clued-up to have had the RT3 test. The NHS lets us down over conversion issues and peripheral resistance, so there may be interest but little else from your GP. Here's a page about the problem and some views about treatment: custommedicine.com.au/healt...

  • Thanks SmallBlueThing, that's a helpful page. I found a full thyroid test online and decided to try it since ive read so many times that normal ranges can be very different according to the individual. I didn't really know about the RT3 thing until the test results came back. One of my symptoms is foggy head and inability to concentrate so when i start reading about thyroid function and all its complicated hormones my brain struggles to understand :)

  • Have you felt hypo throughout your life, or had major stress that could've sent you temporarily hyper (leading to hormone resistance, as a protective measure)?

    It's possible to have normal TSH due to Type 2 Deiodinase working correctly in the pituitary at converting free T4 to free T3, yet the Type 1 Deiodinase isn't providing enough free T3 for us to feel well.

  • No not all my life. Although I have always had a problem with feeling cold and irregular periods but this year the coldness has become severe and other symptoms such as fatigue, memory, foggy head, loss of libido, inability to lose weight are all new. I've always been a very energetic person so this is strange for me to feel so sluggish and tired. I did have a period of time early last year where i tried the 5:2 diet which was just before these symptoms arose, I've heard that low cal diets can be a cause? So that would make sense. Obviously I regret doing that especially as I'm not a fad diet fan. I was in a very stressful situation for the 2 years leading up to it too.

  • I shall give you a couple of links. First if you are having a blood test for thyroid hormones it should be the earliest possible and fasting. If you take thyroid hormones you allow approx 24 hours between the last dose and the test.

    This procedure allows the TSH to be at its highest as that's all the doctors seem interested in and this method also stops doctor adjusting doses to keep your results 'in range'. In range we don't want when on levo as we need a TSH of around 1.

    Never take the word 'normal' o.k. or 'fine' if you feel anything but there has to be a reason.




    Ask him to check thyroid antibodies. If you have them you would have an Autoimmune Thyroid Disease called Hashimoto's.

    If you go to the date March 24, 1999 on the following you can read about RT3.


  • Thank you Shaws. Those links have been really helpful. I couldn't access the web archive link though? Can i go back through and search for it?

  • I can access so don't know why you couldn't but this is the link. Let me know if it works this time:


  • These ratios really are a red herring, and not very helpful. Your rT3 is low, that's what's important. It isn't causing problems if it's low. But, rT3 is transitory, anyway. It eventually gets converted into T2.

    I think your problem is more likely to be your low FT3. It is quite low, and could be too low for you.

    You need to keep an eye on your thyroid. Test about every six months to make sure that your FT4 and FT3 don't drop below range. And, next time, it would be a good idea to get your antibodies tested. :)

  • Thank you greygoose, that's particularly helpful. I did have antibodies tested too and all was normal there. Do you know if there's a medication that they can give to help with low FT3 or if there's anything i can do to help myself? :)

  • For low T3 you need to take T3. However, your FT4 is pretty low, too, so perhaps all you need is a trial of levo (T4) because that will be converted into T3.

    However, the problem there is your low TSH. I cannot imagine any doctor giving you a trial of levo with that low TSH. Unless you suggest to them that you might have secondary hypo...

    Secondary hypo is where you have a problem with the pituitary, rather than the thyroid gland itself. The pituitary, for some reason, isn't producing enough TSH to stimulate the thyroid gland to make hormone. Doctors think this is rare. But, anything will be rare if you never test for it. And, they can test for it if they feel so inclined! What you have to do is make them feel inclined! But, first, you ought to do some reading, and find out exactly how the thyroid works, and how to treat it. Otherwise, they will just brush you off. You need to know what you're talking about before challenging them.

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