Log in
Thyroid UK
91,701 members106,001 posts


My last blood result showed RT3 of 29 (10-24) and the reverse T3 ratio of 8.55.

My TSH is 1.4 (0.27-4.20)

T4 18.2 (12.00-22.00)

T3 3.81 ( 3.10-6.80)

My problem is I continue to have muscle pains, I`ve supplemented Vit D and B12 and now wondered if the RT3 could be causing the pains?

If so I`m ready to try T3 but hope someone could message me a reliable source? Thank you ...any advice would be really appreciated to help stop these pains

17 Replies

What are your current levels of B12 and Vit D?

How much are you supplementing?

Are you also taking a B Complex to balance all B vitamins and D3's important cofactors K2-MK7 and magnesium?

What are your folate and ferritin levels? All nutrients need to be optimal for thyroid hormone to work.

1 like

Thank you for your reply SeasideSusie.

My Vit D was 23.2 (50-100) in August. Too low I know but I began supplementing since and the last check it was 63 but that was in November so I imagine its even higher now. I`m carrying on with adding it.

My B12 was 181 at the same time and I`m supplementing that too but I havent had that checked . I`ve also begun magnesium but only this week and intend to add iron as well.

Do you think the low Vits could be the cause of the RT3? And could the high RT3 be the cause of the muscle pains? I`m afraid I`m not very knowledgeable about all of this, I`ve begun researching but still at a loss and would value your opinion whether adding T3 maybe whats needed ...or would/ could getting my vits to optimal solve my problem?

I take levothyroxine 100 mcg five days and 75 mcg for two days. I`m not tired but just have muscle pains.

Many thanks for your help.


One of the causes of high rT3 is a high FT4 from taking too much Levo and it makes rT3 rather than FT3. I had this, I was still symptomatic and my then GP kept increasing my Levo, eventually I ended up with FT4 of 30 at its highest (top of range 24.6) and FT3 wasn't tested. When I tested everything myself my FT4 was way over range - 165% - and FT3 only 50% and rT3 very top of range. That doesn't seem to be your problem

Other causes can be stress, illness, injury, very low calorie diet - see this article stopthethyroidmadness.com/r... I don't think low vitamins alone is a cause but I won't swear to it. Vitamins and minerals need to be optimal for us Hypos for thyroid hormone to work.

How much Vit D are you taking? You need to get your level up to 100-150nmol/L which is the level recommended by the Vit D Council. When taking D3 we should test twice a year to keep within the range, personally I keep mine at the top end of that range. But you also need the cofactors as mentioned. Magnesium helps your body to use the Vit D and K2-MK7 directs the extra uptake of calcium to bones and teeth where it is needed and away from arteries and soft tissues where it can be deposited and cause problems vitamindcouncil.org/about-v...

Vit D being low is the usual culprit for muscle aches and pains, but other vitamins and minerals may be involved - magnesium, and maybe potassium - eating a banana a day will help potassium levels.

Your B12 is worryingly low, that may be a factor in your muscle pain. You need to check for signs of B12 Deficiency b12deficiency.info/signs-an... and maybe get intrinsic factor antibodies tested to see if you have Pernicious Anaemia. First steps when B12 is that low rather than self supplement. And if you do supplement B12 then it's a must to take a B Complex as well to balance all the B vitamins as they all work together. And as folate and B12 work together you need that to be at least half way through it's range.

Why iron? Have you tested ferritin?

With your current test results for thyroid, personally I would increase your Levo, initially to 100mcg 7 days a week and retest in 6-8 weeks. Most of us feel best when TSH is 1 or below and free Ts in the upper part of their ranges. You also need the following nutrient levels:

Vit D: 100-150nmol/L

B12: top of range, even 900-1000

Folate: half way through range

Ferritin: minimum 70, recommended half way through range

Also, to help conversion of T4 to T3 (as well as optimal nutrient levels) supplementing with selenium L-selenomethionine 200mcg helps.

If your FT4 gets up to 19+ and your vitamins and minerals are optimal, then if your FT3 is still low consider adding T3.

My opinion only of course, as I am not medically trained, but I have had, and dealt with, nutrient deficiencies and poor conversion.

1 like

Thank you once again SeaSide Suzy.

I believe my vit D could well be close to 100 now, I`ve been supplementing B12 so hopefully that is better now too. I eat brazils daily for selenium and will be sure to have another private blood test to recheck everything. I eat bananas daily and drink lemon in water for vit c and have just begun adding magnesium. I`m thinking of adding a small amount of T3 anyway but am having a problem sourcing a reputable place to buy some. Could you point me in the direction of a reputable supplier please?


You won't know what your Vit D level is until you test, and you haven't said how much you take. As we use up our store of Vit D through the winter, due to not being able to make any ourselves from the sun, we often need to take more during the winter. To maintain optimal level I take 2000iu daily in summer and 3000-4000iu daily in winter.

I still maintain your B12 level is far too low to self supplement, you should have investigated further and you haven't said if you have signs of B12 Deficiency.

As for Brazil nuts and selenium, they need to be grown in selenium rich soil to contain any. The packaging needs to state 'Grown in selenium rich soil', if it doesn't then there will be no discernable amount of selenium in the nuts.

For best amount of selenium the nuts need to come from Eastern Amazon or Central Brazil. See the following article with table of selenium content of Brazil nuts


If you can't get nuts stating these facts then you will not get any selenium from them. Supplementing with selenium L-selenomethionine 200mcg daily is the best way to know you are getting the right amount.

1 like

Oh sorry, I missed that bit. I supplement 1,000 I.U daily with D3 and am taking Solgar sublingual B12 daily too. I`ll buy selenium now though .


If your Vit D was 63 at last check and you take 1000iu daily, then I doubt you will be at 100nmol/L now. 1000iu is just about a winter maintenance dose for some people with an optimal level, it's not really enough to raise the level.

1 like

ps ...my latest Vit D test was in Nov and was 63 and I`m having private test to check what it is now. I imagine/hope its even higher but a good improvement from August.


Thank you ...we both posted at the same time. I`ll increase the Vit D


This is a link and read the second question/answer re RT3



Thank you shaws....I`ve read it and from what I gleaned the RT3 wouldn`t be the cause of muscle pain? Have I read it correctly?


Adding......would adding a small amount of T3 help my lower T3 result anyway. Sorry I`m completely lost as to what to do ...and thank you for your time.


If it was my decision, I'd certainly add some T3. More research has shown that a combo of T4/T3 is beneficial for many.


Muscle pain might be caused by too little T3 and depending on your dose of levo to convert to sufficient. Keep in mind I'm not medically qualified.

1 like

Thank you so much, I appreciate you`re not medically qualified but I`m sure you probably know more than most gp`s. My T3 is definitely too low so would like to trial some T3 ....have you any idea of a reputable source please?


You could very well be low in zinc, and that will cause muscle pain. Try taking a little.

I think your high rT3 is caused by your conversion problem, so lowering your dose of levo and adding in some T3 would help that. But it is believed that rT3 is inert, so won't be causing your muscle pain. :)

1 like

Thank you greygoose. I am absolutely in the dark about all of this. I am trying to find a reputable source for T3 would you please know? I`ll add some zinc...again thanks

1 like

You may also like...