I have seen but can’t now find posts that explain how T3 doses relate to t4 as an equivalent
I am soon going to be starting a T3 trial. I was overmedicated on 150 T4 both in my biochemistry and symptoms. I was under medicated on 112 mcg and I wasn’t on 125 for long enough to know.
Endo is advising 125 T4 and 10 T3 but my hunch is that will be too much and I should go 112 T4 and 10 T3. I know the T3 will reduce the T 4. Could anyone please give me the formula to aid me in deciding on a starting point?
TIA
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Pearlteapot
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Sorry, I am innumerate. If the ratio is 3:1 does that mean 90mcg levo has the equivalent impact to 30mcg lio? Or does the ratio of 3:1 refer to the natural ratio in the body that we are trying to emulate?
The study shows that 30 mcg liothyronine will have the same effect on TSH as 90 mcg levothyroxine when split into three doses daily. So, this is the best measure we have of the relative potency of liothyronine and levothyroxine.
It so happens that the natural ratio of free T3 and free T4 is also around 1:3 but this is pure coincidence. The natural ratio of total T3 and total T4 is around 1:50.
In general if you start taking 10 mcg liothyronine you should reduce your levothyroxine by about 30 mcg and preferably split the liothyronine into two or three doses daily.
Although T3 has been a life-changing drug for me, I didn’t get an immediate transformational response to it. About 3 weeks. Not what I expected, and perhaps not what others expect either. I don’t know how common this is? So my impression is that the starting dose isn’t so critical, but reducing T4 dose is sensible as you can’t reduce levels quickly due to long half life and over treatment is pretty unpleasant.
I take on board everything that jimh111 says. I am certain I was under dosed at 100mcg per day and very much over dosed at 125 mcg. My blood test got a stern warning from the site’s doctor and told me to ring 999 if I had any symptoms, such was the level of my T4 but I was able to say “Pah!” because by the time the result came, I had fiddled with the dose and actually felt WELL! I have settled at 112.5 mcg for the moment but feel underdosed. I feel like my response is annoyingly sensitive. I am seeing a private endo very soon and hoping for a trial of T3. Even if I go for the 5 mcg two times per day I will be starting lower than that (hope the pills can be cut). I have just read the wonderful paper tuppence has highlighted today making much of our individual needs and I think responses to the necessary hormones. A ballpark estimation is very useful but our responses may not fit a particular pattern as such and I just think, no matter the ‘guidelines’ we all have to be careful. I want as few repeats of my last overdose as possible. It’s the absolute pits to feel like that! I have to say again thank goodness for the forum where we get all this help. Thanks jimh111 for your knowledge and you @Pearlteapot for bringing this up today. It’s heartening when you find someone making similar decisions on the forum.
I agree with Jim. It is a rough guide though as everyone is different so don't be too fixed on it. I'd split your 10mcg into 2 doses. This is because Liothronines bulk of action is 5hrs so taking an afternoon dose will top you up.
Having said that there are people who find that taking it all in one go first thing is the best way for them. We are all different!
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Equivalent dose of t3
Where to buy NDT, how to come off T3/T4 and dosage equivalencies
Confusion about NDT levo equivalent 
No, 25 mcg of L-T3 Liothyronine isn’t equivalent to 100 mcg L-T4
