Thyroid UK
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Come into a ward round with me please? What dose of t3 and t4 should I aim for?

I need to inform my psychiatrist on Monday on how much liothyronine he can give me without becomeing thyroidtoxic.

My latest levels were on 200 mg levothyroxine and the tsh is 0.2

Free t4 is 25 pmol/l

And free t3 is 4.7 pmol/l

I'm a 36 year old man kg 107and had a total thyroidectomy.

So though I have no thyroid, the intention is im also being given liothyronine for treatment resistant depression, and I am not happy with being given 10micrograms of liothyronine and reducing levothyroxine by 25mg..... the question is what would you recommend the amounts (the ratios of liothyronine and levothyroxine) just to be healthy as a clued up consumer..... ignore the need for increased liothyronine need for the depression for now, I need to give the psychiatrists a soound starting point.

I would like this info as my psychiatrist is not a psychoneuroendocrineologist and is giving dosages of liothyronine according to an endocrinollogist who used to / still only belive s in t4 levothyroxine treatment! Your views are exceptionally valued and may help others to come! Thanks again. Wish me luck on Monday, . Michael.

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I shall give you a link. You may well be resistant to T4 altogether and need T3 alone. Have they tested your Free T3 by the way?

This doctor had the 'perfect' way to treat those of us who are left by the wayside and even resigned is Licence so he could treat his patients as he was more concerned in getting them to good health rather than 'fit' into blood tests.

I shall give you a link of the equivalence of T4/T3 and some links by Dr Lowe who has since died of an accident. Go to page 80 and on the left-hand column (top) you will see the recommendation:-

If you take T3 alone many Endos believe it will cause us harm but Dr Lowe (he was resistant) took 150mcg of T3 in the middle of the night and was able to publish:-

He was an Adviser to Thyroiduk and this is is C.V. Some links within the topics might not work.

I follow his protocol of T3 once daily - I was just very unwell on levo more so than when I was finally diagnosed with a TSH of 10h with many more symptoms particularly going to the A&E so often with severe palps. Since being on T3 I haven't seen a Cardiologist since and heart calmed immediately.

I wish you well as mis-information has been going around for years about T3.


10 mcg liothyronine (L-T3) is equivalent to about 30 mcg levothyroxine (L-T4). (Although in the blood the ratio is closer to 1:4 it is different for tablets due to differing absorption and half-lives). However, 200 mcg levothyroxine is a little too much because as your fT4 goes over the upper limit of the reference interval you start to produce extra 'reverse T3' which blocks the action of T3.

If you were on L-T3 only a normal person would need around 40 - 50 mcg daily (best in two divided doses at breatfast and bedtime). I would start on 10 mcg L-T3 and drop the L-T4 by 50 mcg, just because it is a bit too much at the moment. After that swap about 30 mcg L-T4 for 10 mcg L-T3. Beware that the half life of L-T4 is about seven days and L-T3 a day or two. So, I'd skip a days L-T4 before introducing the L-T3 dose increase. This will smooth out the migration process.

There are studies that show liothyronine is sometimes helpful in overcoming depression which is refractory to antidepressants. These patients tend to end up on mainly liothyronine and little or no levothyroxine. If it makes no difference it is better to be on levothyroxine as it gives a more even dose and is very much cheaper, but getting better is most important.

Note that I am a patient not a doctor.

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Unfortunately, the powers that be think 10 mcg liothyronine is equivalent to 50 mcg of levothyroxine, but that tallies with the suggestion in your second paragraph.

See p.3 derbyshiremedicinesmanageme...


You are so so SO Helpful! Thanks. That's good good advice and with a programe too..... you make a lot of sense a and I think I can agree with what you say..... you are very help full. Hopefully I get some more concurring advice I can give the psychiatrist to make him see through the endocrinologist who only believes in levothyroxine. Thanks again. Michael.


Hi there, this is so hopefull, but is what I am reading correct to say that you recommend lowering the l- t4 by 80 and increase the l-t3 by 20 as a treatment for the resistant depression and having no thyroid what so ever? as I have read in treatment resistant depression 20 to 50 micrograms of liothyronine is given ( ADDED). (Obviously when having afull functioning thyroid).

And the 20 l-t3 you say to take is like 60 l-t4 plus the 120 l-t4 is a total of l-t4 180 witch sounds fine because I suspect I am slightly over medicated on l-t4 200 ( but not bad in range) But that means nothing is being 'added' for the depression. do I now not need to add the 20 to 50 micrograms of liothyronine recommended for the depression on top of the 20 t-3 and 120 t-4.

Many many Thanks for your advice. You are proving most helpful. Michael.


I just thought that ratios of the t3 to t4 would be higher and I would expect at least 20 micrograms of liothyronine and then t4 meds to fit in? But I could so be wrong, or just prechharged with the knowledge that in refractory depression 20 to 50 micrograms of liothyronine is needed to be added so then in my case levothyroxine can thhen be taillired to suit the rest of the picture. I think I need 30 micrograms liothyronine and 100 levothyroxine, witch is kinda 220 mg levothyroxine, kind of..... and the point of the refractive depression treatment is to 'take the average Joe with no pre,existing thyroid condition and add 20 to 50 micrograms of liothyronine. To it.


Many recommendations suggest 10 mcg liothyronine is equivalent to 40 or 50 mcg levothyroxine. These are based on studies that measured the relative effects of fT3 and fT4 in the blood. This was rather silly. Liothyronine absorption is around 95% whereas reported levothyroxine absorption varies from study to study but is around the 50% mark. Thus much more liothyronine gets into the blood. On the other hand the liothyronine half-life is much shorter and so not so much builds up in the blood. This is the only study that has been done and it shows a 3:1 ratio.

Mike, It's true that liothyroine for antidepressant refractory depression is given to patients with healthy thyroids and so is on top of their normal thyroid output. However, as the liothyronine dose increases their TSH falls and stimulates the thyroid less. Thus their thyroid output falls. I guess they end up with hormone levels above normal, this is not desirable as it increases the risk of atrial fibrillation and bone loss in the long term. In a way you are better off in this respect in having no thyroid as you are less likely to be overtreated when using liothyronine for antidepressant refractory depression. I suggested reducing your levothyroxine by 50 mcg and adding 10 mcg initially as this will bring your hormone levels down a touch.

The general idea is to use as little thyroid hormone as is necessary to treat your hypothyroidism AND your refractory depression. If you are OK with just some levothyroxine instead of all liothyronine then this is preferable.

Nobody knows why T3 helps with depression. It could be that there is some sort of mechanism that facilitates the action of the antidepressant. It could be that the depression is due to hypothryoidism (in the brain) and levothyroxine does not resolve this (the brain regulates T3 levels very closely, so taking T3 will to some extent bypass this regulation). This is possible as these studies have used up to 60 mcg of liothyronine which is a large dose in patients with a healthy thyriod.

If you partially respond to liothyronine you may need larger doses, if so your doctor should take care to check for signs of hyperthyroidism and montitor your heart. Note I say take precautions not dismiss the possibility. This is looking some way down the line. Initially I suggest you gradually migrate to liothyroine over a period of months and keep a diary of your symptoms.


Thank you thankyou tank you. I'll write a diary from now.


Michael it's good to see you back.

Apologies if anything is duplicated here, I got a little confused with my links. I'm going to post first and then double-check the links are correct.

What you really need is for someone who knows what they're looking for to treat and test you and to keep an eye out for physical hyper signs as it is impossible to predict how you'll use the meds, but studies do state the dose trialled and maybe that will act as I guideline. I'm sure you're eager to get back on t3 asap and I hope your psych listens.

This study used 20-25mcg for the first week and 40-50 thereafter:

This one says up to 50mcg t3 can be used:

This paper confirms that t3 therapy is superior to levothyroxine in treatment of depression and they use the same gauge for dosage (5-50 having been used in studies):

I hope there's some useful info here.


Thankyou. I feel better prepared for Monday. So many posts from just a thread made on Saturday thankyou all so much, what a community! I am just going to print all these threads and show him on the day. I always feel he has no time for me, but if only he re vampEd this treatment I need for depression it will help so many many others...... time spent now, researching- less blood Sweat and teers all round.


Good luck for Mon.

May I make a suggestion? This forum is to some doctors what a cross is to a vampire, so if it is possible (and I know your internet access can be rubbish there) you might benefit from printing the actual medical studies and academic papers. It might be more convincing to him than what he may consider a load of swivel-eyed internet amateurs with too much time on their hands. That's my take anyway. :-)

Let us know how you get on. Will keep fingers crossed for you.



I love your metaphor ;)


I've found the following:

- An article on DI02 gene variation which argues why some of us need T4/T4 or T3 therapy:

- An article about T3 augmentation therapy in "major depressive disorder". It talks about adding T3 to antidepressant medication (You may feel that you do or don't need to take ADs):

- Another article on adding T3 to antidepressant meds:

- An abstract of an article on hypothyroidism and depression:

I hope it helps. Good luck tomorrow!

Take care


I have copied the part of equivalence from the earlier link.

Journal of Orthomolecular Medicine Vol 28, No 2, 201

Dose Selection in T3/T4 Study RCTs. The second logical basis for a conclusion

is the actions taken, i.e., the doses given to the subjects. Most subjects received T3 below its adult starting dose of 25 mcg/day.

The subjects in RCTs received T3 in some ratio to the withdrawn T4. The various RCTs used T4:T3 ratios of 14:1, 10:1, and 5:1. Subsequent research by the US National Institutes of Health (NIH) found the therapeutic equivalence was 3:1.


Shaws, I don't understand this bit. A starting dose of L-T3 is not 25 mcg, I'm not sure where they got this idea from. Also, they seem to be confusing the ratios of T3:T4 in the blood of a healthy person with the therapeutic equivalence of T3 and T4. I'm unable to find even an abstract for this reference, where did you get it from?

The trials were restricted to patients with unequivocal primary hypothyroidism and so do not apply to other forms of hypothyroidism or treatment of depression.


I'm not a scientist or medically qualified but if you didn't read the link above, that's where I quote from and here it is.


Mike, I'm drifting off topic here so please feel free to ignore this.

Thanks Shaws. I have a copy of that paper but never got around to reading it fully. It is more a critique on process rather than a scientific document.

The reference to 25 mcg being a starting dose comes from the Cytomel website where they are referring to liothyronine only treatment, not when used with levothyroxine. Also, I suspect they chose this because their formulation comes in 25 mcg tablets.

The reference to 14:1, 10:1 and 5:1 ratios refer to the ratios of tablets ingested e.g. 140 mcg L-T4 + 10 mcg L-T3 and not to the relative potency of T4 and T3. The author has misunderstood this point. In any event the endocrinologists are being stupid as they are trying to match the ratio produced from the thyroid directly into the blood with the ratio from tablets that have various absorption factors before entering the blood. The ratio you put in your gob isn't the ratio you get in the blood.

About half the studies reduced the L-T4 and then titrated L-T3 to obtain a similar TSH. These studies are valid (for the cohort - patients with primary hypothyroidism). The other half of the studies used 4:1 or 5:1 ratios. e.g. reduced L-T4 by 50 mcg and replaced it with 12.5 or 10 mcg L-T3. These studies were a waste of money.


Hi Mike. I developed treatment resistant depression when I became hypothyroid. Levothyroxine made no difference, nor antidepressants. I eventually saw a psychiatrist who prescribed liothyronine. She said the therapeutic doses for depression are 20-50 mcg. In the event I started on 5mcg and within 5 days my depression lifted!!!! I am now on 7.5mcg. And coping. (I have trialled ndt and my mood was fine on that too as it contains t3). So push for the lio and start low. You can always raise it gradually and reduce Levo according to symptoms. I've read that people who've had whole thyroid removed often need both t4 and t3.


Thankyou for your kind reply, I'm just a little worried if 10mcg L-T3 dosent work..... because my endocrinologist doesn't believe in t3 she has hinted that I could go thyroid toxic at these levels .!! lol to the psychiatrist so he is taking her lead that no more than 10mcg of L-T3 can be added lol, though I gave him some very very good evidence between 20 and 50 could/should be added! And it just annoys me that b4 talking to the non believing in t3 endocrinologist he wanted to give it to me 20mcg t3 three times a day!...... That's what he would give a 'normal patient' who still had a thyroid, and most 'normal patients' of his have thyroid lab ranges within norms! Just like mine! It annoys me a silly ( could say witch ) of an endocrinologist has put the heebee gebees up him.... ! It is October though I suppose!



I was prescribed 3 x 20mcg Liothyronine after thyroidectomy while I waited for RAI. I currently take 75mcg T4 + 30mcg T3. I have found T3 beneficial in improving depression.

Psychiatrists have prescribed supra physiological doses of T4 or T3 in the treatment of depression refractory to anti-depressants but endocrinologists have always been averse to thyroid medication being used for the treatment of depression and other non-thyroidal illness.


Yes, you are so true, the person that bridges the gap, as I was told on here, by a really helpful member is a 'psychoneuroendocrinologist'. I hope my psychiatrist ups my dose, as I had a lot of 'light bulb 'on'' effects before when trying it..... but then my t4 meds was higher by 75-100 mcg..... but I know it was the t3 that did it. I hope he heeds the advice on here, and does not turn into an adverse endo !! thanks for your replies as always.

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Potentially the problem with a whole load of these studies is that a lot of times either too much OR too little t3 was added and this will skew the results.

Not telling you anything you don't already know, but if your doctors had a good grip on the facts about t3 they would be more confident about how to treat you. Basically they're saying 'Hmm, don't want to find out more about this thing I don't know anything about, I guess it's better for everyone that Michael goes without.'

Sorry, rant over.

The beauty of using t3 for depression is that the results are QUICK unlike the usual fag of waiting up to six weeks for an SSRI or three weeks for an MAOI to kick in.


I will keep my fingers crossed that everything goes well for you on Monday (and in the future!) I wish it was more common for psychiatrists in the UK to prescribe T3 for so-called " treatment resistant depression". I used inverted commas as I hate this diagnostic term. An "inappropriately managed hypothyroidism" sounds more appropriate to me! Take care and all the best x

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Thanks kitten, I think with some 50 years hindsight we will be able to attribute much more mental health to hormones and they wont be viewed as something that simply makes some one 'hormonal' because that seems to be all the power these people believe hormones have at the moment.... sillies .!!


Take a look at the website of Kelly Brogan 😊


The sooner is happens the better. Strangely, I have higher hopes for psychiatrists as being able to notice the link and take more interest in how our biology, e.g. hormones, affects our wellbeing. Many of them are also under the thumb of big pharma but there are others who actually want to help. Sadly they probably feel less competent in prescribing hormones e.g. T3. Endos seem to think that mental health is not their business and yet they hold the power to prescribe hormones... The way docs are educated in their med schools needs to change! All the best of luck tomorrow. At least You know what type of meds (=T3) you need to get better. I hope you doctor will listen! Take care


Hi again.

This might be just the thing. It's simple to read (so you're not asking the psych to parse a dozen complex studies), they're saying to treat w titrated dose of 25-50mcg and there are instructions for how to dose and how to monitor your progress:

There are cautions re 'low tsh' *yawn* but they specify that some groups (eg postmenopausal women) are at higher risk and all in all it seems balanced rather than designed to scare your doc.

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Not forgetting the NHS document I linked to, above: derbyshiremedicinesmanageme...


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