Thyroid UK
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Is this a T3 conversion issue?

I went to my GP for a blood test as been feeling ill for a few months, went from going to the gym 4 or 5 times a week to being too exhausted to get through the working day, making many mistakes at work and now sleep most of the time I am not at work. Along with weight gain, cold, muscle aches, depressed etc. My GP has said that I'm actually overactive and wants to reduce my Levo from 200mg to 175mg to bring me to the normal free t4 range. I was overactive for years before thyroidectomy and know my symptoms are nothing like my overactive symptoms.

I only went up to 200mg levothyroxine last year during a severe depression spell where I was suicidal and wanted antidepressants to get through the day. A different GP suggested I upped my Levo as well as my T4 was only in the mid range and suggested some patients will feel better at the higher end of the range. I'm not sure if the antidepressants or Levo increase worked best but I did feel better and stopped taking anti- ds within 3 months. However, I have since moved towns and my current GP does not seem as clued up.

After this appointment where she decreased my meds, I went for a private blood test as I did not believe my current health reflects being overactive, the results are below. As far as I know I have never had t3 measured before. Any opinions from those more knowledgeable about my results. Going off some reading on here I see that others feel better with free T3 in the upper quartile of the reference range, whereas I am in the bottom quartile currently.

I am obviously going back to my GP with these results, although am having to wait a month for an appointment as it is non-urgent, although I will continue on my 200mg dose for the time being. Also, are there any other tests or investigations I might need to ask my GP to begin so I can get back to feeling better soon?


TOTAL THYROXINE(T4)143nmol/L 59 - 154


FREE THYROXINE* 22.4pmol/l 12.0 - 22.0

FREE T33.9pmol/L 3.1 - 6.8



Thyroglobulin Antibody40.7IU/mL 0-115

Method used for Anti-Tg: Roche Modular

Thyroid Peroxidase Antibodies10.2IU/mL 0 - 34

Method used for Anti-TPO: Roche Modular

12 Replies


FT4: 22.4pmol/l 12.0 - 22.0

FT3: 3.9pmol/L 3.1 - 6.8

FT4:FT3 ratio = 22.4 : 3.9 = 5.74 : 1

Good conversion takes place at 4:1 or below.

I agree that you have a conversion problem.

Continuing with your current dose of Levo and your FT4 remaining high or even increasing, and you could risk making rT3. You really need a bit of a reduction in your Levo and the addition of T3 to bring your FT3 up into the upper part of it's range. I doubt your GP will agree or even understand this, so it would be an idea to ask for a referral to an endocrinologist. Ask for the list of thyroid friendly endos, and ask for feedback on the forum before making an appointment.


Thank you for replying, and I was unaware about rT3 apart from just brief glimpses of it on these forums, so I will go away now and do a bit of further study so get a bit of a better grasp on the risks of this.

Unfortunately I am in no position to see anybody on a private basis atm so I will chance it with the GP armed with these test results and some recent research in the area, but we all know how that can be a risk as some doctors do not like it when patients attempt to become well informed about their own conditions. If there is no joy there then hopefully I will be in better financial shape in a few months to see a knowledgeable endo. Has anybody on the forum got any experience with this and can give me an approximation of costs for consultation and private prescription?


Bumble2017 I didn't mean see an endo privately, I meant ask your GP to refer you to an NHS endo, they will be on Louise's list as well. There is the occasional endo who thinks outside the box although there hands do seem to be becoming more and more tied with regard to prescribing T3. Some have even said that they can't prescribe T3 and have suggested self sourcing! This is why you need to ask for feedback for any in your area, no point in seeing one who is TSH only obsessed.

As far as Magsyh's suggestion is concerned, definitely supplement with selenium, recommended is 200mcg L-selenomethionine. Eating Brazil nuts isn't always the answer. If you can find some where the pack says 'Grown in selenium rich soil' then fine, two or three nuts a day may help, but unless it says that they won't have been grown in selenium rich soil and there will be no selenium in them.

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Oh sorry, I misunderstood, that is a good suggestion and I was not aware that I could ask my GP to refer me and assumed that they would be the only people who could suggest that. I had a great endo whilst pregnant, although I have since moved towns so doubt I could be referred to the same consultant but hopefully I could be lucky again.


My personal opinion is that is someone has had a TT, they should be given a combination of T4/T3. from the beginning

Your results above would appear that you aren't converting T4 to sufficient T3.

T4 is inactive and its job is to convert to T3. T3 is the only active thyroid hormone that is required in our billions of receptor cells otherwise our body cannot function. The brain contains the most receptor cells. Your FT3 is at the bottom or fthe range.I shall give you a link and you will see FT4 and FT3.

Everything is o.k. on paper and I bet your doctor will not have any understanding that we cannot function with a T3 at the bottom of the range instead of the top.

He should reduce levothyroxine and add liothyronine in a 3 to 1 basis on a trial period. Recently they've been told not to prescribe T3 but you need it on a clinical basis as yours is at the bottom of the range.

(I am not medically qualified - I am hypothyroid which was undiagnosed/untreatd).


Thank you for your reply. Really interesting to hear your opinion about supplementation with both T3 and T4 after total thyroidectomy. I had never really considered this before, although have been mostly well in the nearly 4 years since surgery, although I have always struggled to lose weight and eventually stopped trying as although I am overweight, at least I wasn't gaining any more weight in that time. Without regular T3 screening for thyroid patients, it is impossible to tell how many of life's pains and niggles could be avoided with a little bit of medical intervention.

How is your health now if you don't mind me asking. Were you able to get the correct treatment, or have you self-treated at all?


I am very happy to be fit and well and am on T3 only. I have bought my own T3 for a while now although my GP did prescribe until Amdipharm (Mercury Pharma) ran out of T3 altogether,and there was also complaints about it, so there was quite a bit of consternation amongst those prescribed.

My doctor wouldn't prescribe either of the other T3's which are available on a 'named-person basis' as they'd have to take responsibility. So, to please myself and not cause me aggravation I've been sourcing my own.

Now the the Authorities have said it cannot be prescribed - due to cost I believe but it was the perfect excuse as more were asking for it.


Both T3 and T4 need to be mid levels . Some need a little higher . Our brain works mostly off T4 . Some who dose with more T3 then is needed for them they can become lethargic or T3 drunk feelings . And even become Estrogen dominant with high T3's . Even character changes they become aggressive, hostile ,anxious, and argue a lot .

The take home lesson is "EVERYTHING IN MODERATION ".

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I agree you are not converting your t4 into ft3 very well. Have you considered trying supplimenting with selenium. It is essential for conversion of t4 to ft3. You must be careful as too much can be toxic. If you want to try the natural way eat a couple of brazil nuts per day. If you start converting better you could then reduce your levo a bit till you find the right dose for you. If that doesnt work t4/t3 combination may be the way to go xx

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Thanks for your reply, any help and advice is so appreciated as I begin to see the light at the end of the tunnel in feeling so down and under thick mud.

I did not know about Selenium but I do take a daily multivit and have just noted that it contains selenium. I do forget to take it some days though as I don't take at the same time as my thyroxine as it contains iron. I will definitely be sure to be more on top of my doses


What a lot of people dont know is that multivitamins should be avoided. An example with the selenium is that selenium and iodine as well as zinc are oxidants. VitA, vitC etc are antioxidants so they shouldnt be taken together as they cancel eachother out. The same as iron should be taken with vit C but not with calcium. If you see what I mean. I took multivitamins and minerals for years and wondered why i still had a deficiency. Multivitamins seem convenient but they are a waste of money. Xx


Totally agree! Plus, they usually only use the cheapest ingredients, and not enough to make any difference to a real deficiency, anyway.


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