Thyroid UK
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A snippet about T3

I went to see my lovely endocrinologist in Sheffield yesterday, and he says (quite rightly) that at present there isn't a "chronologically correct" replacement for T3; we don't yet have a version that can mimic the daily natural rhythm of T3 release. The very short,20 minute half-life of it, means you can't accurately replicate its release by taking the tablets available. However, he also told me that there is current research going on in Sheffield in an attempt to find a better substitute. More power to their elbows I say! I'm reminded again of how lucky I am to have such a consultant working to help me.

8 Replies

Liothronine (L-T3) has a serum half-life of one to two days, see . Research has show that if taken in three doses daily it does not cause fluctuations in TSH. In practice, I suspect taking two doses a day is sufficient. Endocrinoligists tend to confuse the serum half-life with tissue response to the hormone. After getting into the bloodstream T3 goes through a number of stages before it finally acts on the DNA in the cells. These stages act as buffers to even out any fluctuation in serum T3 levels.

The best way to look at is if you drink a glass of water you will pee half of it out within an hour or two. However, if you don't have a drink for a few hours you don't go into crisis. Our doctors do not warn us we much sip a little water every half-hour less we suffer from hypo H20 ism or hyper H2O ism. It's the response to liothyronine that matters, not the amount measured in a blood test.


Hi mumcat2

You are indeed lucky to get T3in Sheffield my sister has just retired as a GP in Sheffield and told me they don t prescribe T3in Sheffield. Perhaps they have at last seen the light.



Glad to hear there is a good endo in Sheffield - I'm currently trying to persuade my GP to refer me for low TSH and low FT3 but he's not playing ball as yet!


Good luck! Perhaps you might offer to supply the ball(s)? Sorry - my sense of humour still thinks I'm 18!


Nice one!


Hi Mumcat2,

I visit an endocrinologist at the Royal Hallamshire, do you see Dr A? He's a nice chap and has just started me on 10mcg of T3 with my T4 after taking T4 for a year with limited improvement in my health following removal of the right thyroid lobe to remove thyroid cancer.


Would he be referring to sustained release T3, all the good brands are in the USA there is a specialist chemist in London that compound this.



Dear Mumcat,

I live in Sheffield and have had a underactive thyroid for years. Who is the endocrinologist that you see? I was on whole thyroid for years, seeing Dr. Hayes Allen, untilo my GP persuaded me to go to the Northern General endocrinology department, They simply persuaded me to give up whole thyroid and moved me onto levothyroxine. After about a year I moved back to whole thyroid as I felt much better on it. Now I am seeing a doctor in worcester, but its not really satisfactory. He is too far away and does not really know me. If there is someone in Sheffield who can see farther than T4 only I would be delighted to know.

Hoping for a reply, Pip


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