Thyroid UK
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I have been on 20mcg liothyronine 3 times a day following total thyroidectomy. Now following RAI the consultant wants me to convert

150mcg thyroxine. There is a 10 day swap over regime. Does this dose seem equivalent? I am prepared to give thyroxine a go as T3 doesn't make me feel normal ie pre TT state. Understand I will have to work hard probably trial and error to achieve a new normality. Any advice gratefully received.

4 Replies

I have hypothyroidism and I would be extremely, extremely reluctant to change from T3 to levothyroxine. Having already been prescribed levo initially and was far more unwell that before diagnosis.

Is the cost of your T3 the issue, as personally I believe someone without a thyroid gland whatsoever is entitled to the best replacement, be it T3 or NDT (which I know very, very few prescribe). T3 is the active hormone required by every cell without which our bodies cannot function.

This link is a bit scientific but this is the conclusion:

Conclusion. In a critique I wrote in 2004,[5] I documented some disturbing findings about T4-replacement: in five studies, it left hypothyroid patients suffering from hypothyroid symptoms.[14][15][16][17][18] And in one study, patients on T4-replacement used more drugs and had an increased incidence of potentially fatal diseases.[18]

Our long line of research shows that some patients with too little thyroid hormone regulation don’t benefit at all from T4-replacement or from T4/T3 combination therapy. Virtually all these patients, however, improve or recover with high enough doses of T3 alone.

On such patients’ behalf, we need to get word of these studies out to their doctors. I hope that doctors who’ve falsely believed that the brain gets T3 solely from T4 will consider the treatment implications of the study results. If so, perhaps they’ll then allow their patients who respond poorly to T4-replacement or T4/T3 therapy to switch to T3 alone, the only approach likely to work for them.

T3 in this country is expensive whereas T4 (levo) is approx £1.50. 20mcg of T3 equals approx 100mcg of T4.

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Most recent research suggests 20 mcg L-T3 is equivalent to 60 mcg L-T4. I think the 4:1 or 5:1 ratios come from reseach that measured hormone levels in the blood and worked out equivalents, but taking tablets is different. The two tablets have different absorption rates and different half-lives. The BNF (journal of drugs) still quotes the 4:1, 5:1 ratios and I have asked them to review this, so that we can get an expert review.

150 mcg levothyroxine is a bit less than 60 mcg liothyronine but if you had thyroid cancer the treatment has two objectives, to replace your missing hormone and to prevent any reoccurrence of the cancer. For this reason they may prescribe more hormone than you would need if there wasn't a cancer. Because of the short half-life of liothyronine they would have to err on the higher side. I'd give the levothyroxine a trial for about 3 months and if you do worse than you are now you can then request that they reintroduce some or all of the liothyronine. Levothyroxine works for many people, others need liothyronine or natural dessicated hormone. Only time and trial and error will tell.


Hi Shaws and jimh111,

Thanks for your replies. The hospital consultant is very anti long term t3 replacement (no surprise) and as I am only 2 weeks post RAI my GP who may be more amenable to combined therapy is unwilling at this stage to take over hormone replacement.

I also have a background in acute care and have colleagues and friends of which about 2/3 manage well on thyroxine only and 1/3 who take t3/t4 combo or NDT. I feel it is not unreasonable to try thyroxine but to keep a clinical diary, basal temp, resting heart rate and BP as well as commenting on fatigue and mood. It is my hope that I can then if necessary persuade my GP to add in t3 at a later date. Of course that may not be possible and I may have to go the self medicating route.


I do hope whichever method you chose, that it works and that your get prescribed enough to give you good health. I think it's when you are kept within a 'range' that may cause problems.

Re your GP adding in T3 later, he may well do that as Dr Toft of the BTA mentions it in an article.


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