Thyroid UK
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Research shows that T3/T4 combo stops working after 3-4 months says Endo

Just had an appointment with my Endo and I basically told her I was self medicating with T3 added to my T4 as I'm not converting T4 into T3. She then said that many research studies carried out by the British Thyroid Foundation have shown that the T4/T3 combo works for about 3-4 months for patients and then most patients go back to their original state of being unwell. It only works for a small minority of patients. I then asked her if I could access these research papers and she replied she was not prepared to go through the internet looking for them and that I should look under "pubmed". My son who was with me then asked her has there been a synthesis of these papers and she replied "No... I don't know". (I've since looked on the internet and cannot find any). I then asked her does the same stand for those on T3 only and she replied there hasn't been any research carried out on those on T3 only. However, she has given me a trial of T3 to add to my T3 for two months and that after that I would need to get it prescribed by my GP and she would inform my GP that she has prescribed it for a short term. I said if what she says is correct then I need to know why I'm not converting and she replied irritatingly, that more or less and in so many words, we would cross that bridge when we get to it.

I would really like any comment on the above and in particular is there any validity in what she has told me.

She also said my cortisol was good and I replied yes, but that is only a blood test that shows total cortisol and not free cortisol. It doesn't show unbound cortisol and her blood test would only pick up Addisons or Cushings and nothing in between - she looked at me blankly. I said I had a Saliva Test Graph showing that I had low free cortisol and she said that it was wrong.

Could someone also comment on my blood test results:

THS: 0.67 (0.27 - 4.20)

T4: 17.3 (12.0 - 22.0)

T3: 3.9 (4.0 - 6.8) L

There was also another comment made re: Vit D.

25- hydroxy Vit D2 <7

25- hydroxy Vit D3 97

25- hydroxy Vit D 97 (25 - 120)

Comments: Assay does not detect Alfacalcidol or Calcitriol

Deficient: <25 nmol/L

Insufficient: 25 - 50 nmol/L

Consider reducing dose >200 nmol/L

Total 25- hydroxy vitamin D is the sum of D2 and D3

B12 471 (191 - 663)

Folate 17.7 (4.6 - 18.7)

20 Replies

Am so sorry to hear your experience though sadly not surprised. The truth as I understand it is that much more research is needed on the efficacy of T3 and many patient organisations have been campaigning for this for years.

However there are plenty of people who do much better on either T3 being added in or T3 on its own - whether that is in a synthetic T3 formulation or in a natural dessicated thyroid tablet. Am on a NDT and have been for 8 years and can categorically say I have only improved with the addition of T3 and have not found the effects have worn off after three months!! The only times I have felt unwell has been when my dosage has needed increasing -generally need more in winter then summer -otherwise been on the same area of dosage for the whole of that period. It sounds like your endo is spouting a belief without actual evidential research to back their claim. You may have to consider going to someone else?

Am afraid I can't help you with research papers. Shaws is on T3 only and is very knowledgeable around this. May I suggest you pm her?


Hi Wavylines. What amazes me is that if what she says is correct then she is implying that T3 would cease working for those on T3 alone as well surely it cannot stop working for them too. Unless I see those research papers I really cannot take what she says seriously.

Thank you for replying Wavylines.


Mischa, I think your endo is making it up about T4+T3 especially as she can't even refer you to the alleged research. I've certainly not seen research to suggest T4+T3 stops working. I've been taking T4+T3 since Dec 2013 and it continues to work just fine for me.

TSH 0.67 and FT4 17.3 are okay but on T4 only you need FT4 higher >19.5. FT3 is below range. Were these results from when you were on T4 only? How much T3 has she prescribed?

VitD 97 is in the optimal 75-200 range and around 100 is satisfactory for most people.

B12 is adequate but most here like to shoot for the optimal 1,000. Supplement 1,000mcg methylcobalamin sublingual lozenges, spray or patches and take a B Complex vitamin to keep the other B vits good. Folate is good.


Hi Clutter: These results were based on T4 75mcg and T3 6.26mcg. I now can see I'm taking way too low T3. She has given me two months of T3 10 mcg to be taken daily the rest will have to come from my GP. It doesn't matter because I will continue to take my own T3 if the GP doesn't prescribe.

I currently take Jarrows Methyl B12 1,000 but only started recently and also take B complex vit by Solgar.


Mischa, hospitals usually only supply a prescription for a month or two and then GP continues the repeat prescriptions.


THS: 0.67 (0.27 - 4.20)

T4: 17.3 (12.0 - 22.0)

T3: 3.9 (4.0 - 6.8) L

These are strange results, did they come from your endo or from a test you did? The numbers don't really make sense, hence my question.


Hi jimh111: These figures are from the Endos blood test which I took last week. I've always been under range for T3 since first diagnosed three years ago - never been in range. However, started self medicating with small amount of T3 (6.25mcg) about seven weeks ago so clearly I need to up the dose.

jimh111 love to know why do you think they don't make sense?


I was thinking the TSH 0.67 was very low but after looking closely (as I should have done) I notice that the lower limit is 0.27 rather than the usual 0.5 or thereabouts. However the TSH is still a bit low.

Looking at some of your earlier posts you have suffered from depression. This can cause TSH to be lower than it should be and lead to lower fT3 also. I would seek to take 10 mcg liothyronine (T3) at breakfast and at night (in addition to your current levothyroxine) and see how you go. This may also help with your depression / anxiety. If you get signs of overactivity such as a slight hand tremour then back off a little. You should point out to your endocrinologist that anxiety / depression lowers the TSH and also produces TSH isoforms which have reduced bioactivity. This justifies a trial of liothyronine.

There is no research that shows T3/T4 treatment stops working after three months although some endocrinologists have speculated so. Speculation is not evidence.


I will only comment on your T3 result - which is 'below' range and others will respond re the other tests. So I am sure you will definitely improve the with addition of T3. This is my personal opinion 'what's the use of taking T4 when it's not converting to sufficient T3"?.

One of our Admins - Clutter - has had T3 added. Never mind about Research it is what makes us well which is the most important fact not the TSH. You can read Clutter's profile here:-

I am on T3 only now and, so far, am well. They are willing to prescribe some medication for our remaining symptoms but don't seem to understand that some of us cannot get well on levo alone and may need our TSH to be suppressed by sufficient and additional hormones. Again that seems something of a problem to Endocrinologists.

I am glad you have fought for a trial and wish you success. I hope too that she hasn't given you too little T3 to be added to your T4..


Shaws, thank you and Clutter too and all of you at Thyroid Uk. What would we do without you. I felt so down when I came out of the Endos office I went into the toilets and cried. Sometimes it can be a lonely and isolating illness particularly when you don't have the health professionals on side. I went in looking for some good news and came out feeling crushed. My son was with me and told me to take what she says with a pinch of salt.


Mischa I'm glad your son is on your side. That's a huge help. Good luck.

1 like

I have just read your response above re your T3/T4 dosage and the ideal according to new research is 1 part T3 to 3 T4, i.e. 20mcg T3 to 60 mcg T4 (although 50mcg would be the nearest in the UK) or 25mcg of T3 to 75mcg T4. Although this deals mainly with (I believe) thyroidectomies you will see this excerpt from the Journal of Orthomolecular Medicine Vol 28, No 2, 2013:-

"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 re


search by the US National Institutes of Health

(NIH) found the therapeutic equivalence was


41 Thus, most of the subjects were under

treated with the T3/T4 combination. In light

of the NIH finding, the conclusion that T3

therapy is never needed is invalid."

In actual fact I have read that too low a dose of T3 might not be advantageous. So the above is your 'pinch of salt' to go onto your Endos comments.


Interesting piece. Thanks Shaw. I would like to take this except and show her the next time I see her.

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I doubt they ever read research papers. They just keep to the guidelines, i.e. TSH and levo and diagnose by TSH only. They are also unaware of symptoms which they disregard.



I think the extract Shaws posted may have come from one of these studies:

These studies discuss benefits of T4+T3 combination vs T4 monotherapy.


Ai think your son summed it up very well. Was this one of Thyroid UK listed ones? If so I would let Louise Warvill know. If you don't have the list you might want to ask her for it to see if you can find a more informed endo -they are a rare breed though!!


No she wasn't from the Thyroid UK list. She is an NHS endo from a well known leading London teaching Hospital. Sad to know.


Of course the doctor lied, it seems they can easily when its thyroid related! Its not true that T3 or NDT stops working its T4 or Levothyroxine that stops working after a while!


Why do you say Levo stops working after a while, why would that be ?


Some of the medical papers are flawed. The time and amount prescribed isn't for long enough or high enough dose, hence these problems and yet there are papers that say NDT works for some patients. They need to do more detailed research and Endocrinologists also need to produce the papers from which they quote.


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