Thyroid UK
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RT3 to Underactive

Hi All

Im back again looking for some advice. Met a new endo who took me off everything for 2 week and did my bloods again.

TSH 7.26 (0.5 - 4.40)

FT4 9.5 (10.0- 20.0)

FT3 4.0 (3.5 - 6.5)

She has put me on Thybon 20 and thyroxine 25.

Still dont feel great at all new thing to develop a really dry itch scalp more hair loss, tiredness as before, no weigh loss, muscle cramps knees murdering me in the evening, Feeling the cold.

Dont know why I changed from RT3 to underactive but results show only slighty underactive im worried when test are done again ill be in normal range but feel far from normal.

Has anyone seen this before.



25 Replies

I don't understand the reference : rT3 to underactive. Where's the connection?

Actually, you are quite a bit underactive, not slightly. You are underactive as soon as your TSH hits 3. But, you appear to be converting OK, so I don't understand her dosing.

You have a lot of symptoms and you can't lose weight, because your FT3 is so low. You'll probably need it up near the top of the range to get rid of the symptoms. :)


Hi Grey goose

My post is a bit confusing I was trying to link it back to my previous post so it would b easier to understand....


1 like

This is my first post;

Hi Everone, Im from Ireland and finding it very difficult to get help. I had a wonderful doctor who sadly passed away he diagnosed me with Reverse T3 which he treated with Liothyronin hydrochlorid which I call Ti-Tre my dose varied from 20mg to 160mg during periods of high stress. Now he has passed away I have no one to help my own GP has continued to supply my prescriptions but I dont know for how long.

The TiTre treats my symptoms like cold hands feet, memory issue, mood, joints improved. I was a disaster I be driving along totally forget where I was going no matter how hard Id try to remember Id have to go home in tears a lot of the time until I remembered it was so frustrating. I couldn't do simple maths or hold normal conversation lose my train of thought. all of these have improved.

My issue that have not fully resolved hot flushes mainly morning but will happen through the day if i get flustered. Unrefreshed sleep full night sleep in bed by 10 wake up so tired pull myself out of bed. Fatigue. Awful dry skin. Tired dry eyes. Hair loss. Bruise very easily. Mouth ulcers.

Latest symptom but i dont know what these relate to is it thyroid or PCOS I have ovarian cysts. Unintentional weight gain. About 3 stone in 1.5 years.

Blood tests

TSH 0.05 0.15-3.2

T4 free 3.9 9.9-20.1

T3 free 19.4 2.7-7.0

TPA 10.0 <35

Testerone1 0.3-1.7

SHBG 565.2 32-128

DHEA 1.9 1.0-11.7

WBC 3.4 3.9-11.1

Day 18

FSH <0.1


Oestradiol <18

Progesterone 2.2

These are just some of the tests if anyone could shed some light or point me in the direction id be so grateful.


I noticed you mentioned Reverse T3 in your previous post and I didn't see the relevance. I also don't see the relevance this time. You haven't given a result for a Reverse T3 test in either post, so how do you know it is a factor in your health problems?

The raw ingredient from which Reverse T3 is made is T4. If you have little or no T4 there is no way that the body can make Reverse T3.

T3 and Reverse T3 are completely different things and the body doesn't convert from one to the other - it is impossible.

Has your doctor brought up the subject of Reverse T3 for some reason? I get the feeling that you've been misled on the subject of Reverse T3 somewhere along the line but I'm not sure where or how. A very high Free T3 result doesn't tell you anything definite about Reverse T3 levels.

Your latest results show that you are hypothyroid.

TSH 7.26 (0.5 - 4.40)

FT4 9.5 (10.0- 20.0)

FT3 4.0 (3.5 - 6.5)

Your TSH is much too high showing that you are (or have been) under-medicated. Your Free T3 is too low for good health. Free T4 is not very important if treatment consists of only T3, or T3 and a low dose of T4/Levo.

Anyone who is hypothyroid and then taken off meds for two weeks will show poor results in a thyroid function test.

Your previous Free T3 result showed that you were massively over-medicated.

Can you tell us why you refer to Reverse T3, so we can clear up any misconceptions?

With the results from your older post I suspect that your Reverse T3 results would have been practically zero because you had very low levels of Free T4, so there was almost no raw ingredient available from which to make Reverse T3.


RT3 is normally treated with Liothyronine because it evades the faulty conversion from T4 to RT3 instead of normal T3. The usual FT3 test doesn't distinguish between the two, so you need a test for RT3.

Thyforon is a version on levothyroxine, I thought it was just a veterinary medicine, because my old dog was on it. No matter, if you are a RT3 producer it will provide the materials to make it, and your RT3 will rise.

I presume the FT3 figure of 19.4 was a typo, because otherwise I would expect you to be/have been not sleeping, losing weight, jittery, if you were alive at all. If it is true then you must be quite resistant to the thyroid hormone. That would tie in with a dose of 160mg of Lio. Increasing the dose for a resistant patient just breeds more resistance, and it may be quite difficult and lengthy to reverse it.

You probably need to give it a couple of months on your new regime and test again, including reverse T3. There isn't really a shortcut when they have been messing around with your prescription. It takes that long for T4 levels to stabilise. Until then we are guessing wildly about a situation that no longer exists.

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Sorry Ruthi you've been told an urban myth. The usual Free T3 test does distinguish between Free T3 and Reverse T3. Diogenes was consulted on this question a year or so ago and he said the Free T3 test does exactly what it says on the tin - it wouldn't have been possible to market it if it didn't measure exactly what it claimed to measure.


Really? I'll remember that in future. Well in that case RT3 still needs to be tested, just no difficult sums.

And that figure of 19.4 still sucks!

1 like

Oh, agreed!


I found one post on the subject with a response from diogenes :

I'm sure there was another but I haven't been able to find it.


But there are references to FT3 falling as RT3 rises (in tests).

No idea where I got the original misinformation from


My understanding...

Both Free T3 and Reverse T3 are made out of T4.

If the amount of T4 is fixed by the dose of thyroid meds or the capabilities of the thyroid gland then if Free T3 rises the Reverse T3 must fall, and vice versa. The amount of T4 is the limiting factor in how much of both there can be.

It's like saying that I have £5 and I am going to spend it all. I want to spend it on jelly babies and liquorice allsorts. If I buy more of one then I must buy less of the other because there is only £5 to spend and it won't stretch any further.


Also, I think I'd be right in saying that the available rT3 tests measure Total rT3, not just Free rT3.

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Hi humanbean

My previous doctor treated me for reverse t3 i do not have results of test i did a blood test which was sent to france at the time to test he did a ratio and told me I was reverse t3 i really didnt question him about it. He treated me with thybon for a few years my dose was monitor by symptoms. We were doing great till he fell ill and passed away so I had 2 years on waiting lists and referral trying to get some one to see me. I continued on the last dose of Thybon he had give me. 2 years on new endo took me off thybon for 2 weeks to get base line and here we are.

Does this help explain it better.



It does.

Some people aren't good at converting T4 to T3. They may end up with high levels of Reverse T3 instead.

In a healthy person who becomes ill with flu (for example), their body may create more Reverse T3 and less normal T3 than usual. This has the effect of slowing people down, reducing their energy, and forcing them to take the time to allow their body to recover. Once the person recovers, the ratio of normal T3 and Reverse T3 goes back to normal.

In someone with chronic illness and/or a thyroid problem the body may get stuck creating more Reverse T3 than it should. This can make it hard for the body to heal, and permanently reduces energy levels. Increasing the amount of T4 (Levo) the body has doesn't always change the ratio of Reverse T3 and normal T3 to a healthy state. Nutrient deficiencies (common in hypothyroidism) may add to the problem. In some cases the problems become almost like a stalemate. Nothing can improve because the Reverse T3 levels are too high and the Reverse T3 levels stay too high because nothing ever improves.

The way out of the stalemate that works for some people is to remove the raw material required for producing Reverse T3 i.e. reduce T4 by taking a high dose of T3 alone. (If the thyroid is still capable of producing some T4 it won't produce any or very much if there is lots of T3 in the body.)

In many cases this treatment is only continued for a few weeks and then T3 dose is reduced. But some people need to continue it indefinitely because their bodies can't cope with low doses of T3 - they have a condition called Thyroid Hormone Resistance.

In other cases, reducing the Reverse T3 levels may make the person feel a lot better, but they don't need the high levels of T3 permanently. They may do well on either T3 alone (but at a lower dose) or back to T4 and T3 together, or NDT, or some other treatment or combination of treatment.

Whichever situation applies to you, when your level of Free T3 was 19 or so, you were dangerously over-medicated.

Your latest tests, after two weeks un-medicated, can't really tell us much other than proving that you are hypothyroid. You would need to take a consistent dose of thyroid meds of some kind for 6 - 8 weeks then re-test. Then you will have something we can work with.

When you do get re-tested can you ask for levels of iron/ferritin, vitamin B12, vitamin D and folate to be measured. They are commonly deficient or low in people with thyroid problems, and most of us feel a lot better when levels are optimal. Don't accept that the results are "normal". There is a big difference between just being in the reference range and being optimal.


Thank you Humanbean

My blood are done again just waiting for results. In November my results were

Ferritin 40 (6.9- 282.5)

B12 513 (200-1100)

Fol 5.3 (3-14)

Only my thyroid bloods have been repeated. My endo has also offered Natural Dessicated Thyroxine Armour as an alternative she said it helps mood and energy.



NDT will only help mood and energy if she gives you enough. And that's usually the problem, they won't prescribe enough to make you well, because NDT suppresses the TSH, and doctors are scared rigid of a suppressed TSH; So, if you do, go on to NDT, be sure not to let her dose you by the TSH. It's the FT3 that is the important number.

Your ferritin is much too low. Have you been supplementing that?


Grey goose

Thanks for info... I'm still learning about all of this... how would you recommend supplementing the iron



Iron is not my subject. :) I would suggest you ask a new question, on just that subject. Then our iron 'experts' will advise you.


Ferritin (Iron stores)

Assuming you haven't supplemented since getting the result of 40 then you do need to take iron supplements to improve your level. The optimal for most of us is mid-range or a smidgen higher. For the range you've been given that would be about 150 - 170.

I can only tell you what the situation is in the UK and hope that you can adapt it to where you live.

Iron supplements can be bought in pharmacies or bought online (or prescribed, but I'm ignoring that option since doctors usually only do that if results are well under range).

Ferrous Fumarate 210mg (FF) comes in boxes of 84. Each pill contains 69mg of pure (elemental) iron and that is the important thing to know about any iron supplement. The maximum dose is 1 tablet, 3 times a day, giving a total of 207mg of pure iron per day. There is nothing stopping you from taking fewer tablets, of course.

Ferrous Sulfate (Sulphate) usually comes in tablets with a similar iron content to the Ferrous Fumarate.

Ferrous Gluconate usually contains roughly half the iron content of FF - about 35mg per tablet.

Ferrous Bisglycinate (sometimes called Gentle Iron) contains about 20mg - 25mg per tablet.

Always check the iron content of any iron supplement you buy.

For more information on iron supplements and info on supplements of completely different types to the ones I've given above :

Some meat eaters eat liver and/or black pudding a couple of times a week to raise their iron and ferritin levels rather than taking supplements.

Every dose of iron should be taken with 500mg - 1000mg of Vitamin C. Iron causes constipation. High dose Vitamin C causes diarrhoea. Adjust the Vitamin C dose to keep yourself comfortable. Another benefit of Vitamin C is that it helps your body to absorb iron.

Iron interferes with the absorption of thyroid meds of any kind. Take them at least 4 hours apart.

Iron is poisonous in overdose, so testing regularly is absolutely essential. Private testing without a doctor is possible in the UK. This is a test which is done with finger-prick testing :

They may accept samples from Ireland. You'd have to ask. Once you get some results post them in a new post and ask for feedback.

Before doing any testing for iron you need to stop supplementing for 5 days to get an accurate result. Also, testing should be done in the same way that thyroid testing is done - early in the morning (before 9am) and fasting except for water.


B12 513 (200-1100)

Fol 5.3 (3-14)

Your B12 may be okay, but it is at the lower limit of okay. Below 500 may cause neurological damage. You might feel better with higher levels. Your folate is also rather low - mid-range is 8.5. Neither B12 nor folate are harmful if you go high in range.

You would probably do fine supplementing with a good quality B Complex which contains B12 in the form of methylcobalamin (NOT cynaocobalamin), and Folate in the form of methylfolate (NOT folic acid).

Some suggestions :

Jarrows B-Right

Thorne Research Basic B Complex

I'm sure there are loads of others.

Many B Complex supplements contain Biotin. If that is the case, then stop taking the supplement 5 days before any thyroid function tests. Biotin may affect the results.


Thanks for taking the time to answer my question...


NEVER let your doctor titrate your meds by blood tests alone demand a full physical examination.


Latest bloods

TSH 1.77 (0.5 4.4)

FT4 8.3 (10.0 20.0)


Hi All

Im fierce disappointed my doctor now says my thyroid bloods are very good and to continue on same treatment. I have contacted endo for another app what will I do if she feels the same I really dont feel good the only thing that has improved is hot flushes and my memory that has improved im not like a mad woman with 40 lists...

The worst still are unrefreshed sleep sore dry eyes waking up and a headache right at crown of head feels like a hand squeezing top of my head, same place had become very itchy and dry recently.. hair loss all over body now inside of my eyebrows are sever weigh gain has slowed down I was putting on a pound a week now since middle of December ive put on 3 pounds. I go to circuits for 1 hour 3 times a week some nights I can plough away through it and other night im so exhasted I find it very difficult but I still try do the ones I can and I walk Sat & Sun. I eat gluten free as I found my photo sensitivity was caused by this. I have a very hands on job I work 3 days a week... My muscles cramp alot and my knees kill me in the evenings can hardly stand up once ive sat down... The biggest thing ive noticed recently is its really aging me i have lines appearing on my face. I dont smoke or drink.. Do ye think all these symptoms are thyroid related... There are more but you know when you try list them all together it can be hard better start list for endo now and as i think of them jot them down...

Thanks everyone for reading....



do a detox diet, you could have been given substances. (poison) juices, no solid food and let your body just feed on nutrients in the juices. if possible. it will help recovery on organs less work for your thyroid as that regulates every function in your body. It will never harm you


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