Thyroid UK
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Hi I am waiting to hear from Endo about starting adding t3 any day now.My GP not sure about it at all ,but will prescribe it and monitor me.

I take 100mcg of thyroxine at present.

Can anyone tell me if it is ok to start adding 10mcg with my 100 of thyroxine once a day in AM for few weeks then add in another 10 of t3 in PM for few weeks then go up to 20 t3 and 100 thyroxine AM and 10 t3 in PM then up to 20 t3 and 100 thyroxine AM and PM

How long should I wait between dose increases.

I cannot find any guidelines for t3 administration.

I am so afraid of getting heart arriythmias .

12 Replies

Your Thyroxine should be reduced when you add T3.


CG, only if the patient is already optimally medicated on T4 otherwise the patient remains undermedicated and T3 is seen as a fail.


Whoops, sorry but I didn't know that. Thanks Clutter for pointing it out.


Susiebow, as you have been having hyper symptoms on 100mcg Levothyroxine although you are undermedicated, I would really advise you to start T3 slowly at 5mcg once daily for a week or two to see how you tolerate it. If all is well you can try 5mcg morning and evening for a couple of weeks. If you are well on 10mcg you can increase to 15mcg, usually taking 10mcg in the morning and 5mcg in the evening and finally 20mcg split into 10mcg morning and evening. I doubt your endo will prescribe more than 10mcg or 20mcg initially.

As long as your FT3 remains within range there is no more likelihood of developing arrythmias than there is on Levothyroxine only.

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Thanks for reply Cutter,very helpful.


clutter what is ideal for within range of ft3 what numbers are ideal pls?


Minus, towards, or in the top third of range is supposed to be optimal.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


Usually they drop 50mcg of T4 and replace 10mcg of T3 (T3 is more metabolically active as it doesn't have to be converted and 20mcg of T3 is equal in effect to around 80mcg of levo ). That's what I had. I take my dose (now T3 only) once daily and this is an excerpt just in case your Endo isn't sure.

July 12, 2010

Question: I’m perplexed. You say that T3 can be taken alone without T4, but my endocrinologist insists that our bodies absolutely must have T4 along with T3. He says quite emphatically that without T4 in the mix, I won’t get the full benefits of my thyroid hormone therapy.

"Dr. Lowe: I respectfully disagree with your endocrinologist. Studies indicate that T4 is of no use to anyone except, figuratively, as a storage unit for the metabolically-active thyroid hormones T3, T2, and possibly T1. When T4 ends its long ride through the circulating blood, it enters cells. There, enzymes convert it to T3, and, after a while, other enzymes convert T3 to T2. The T2 becomes T1, and eventually T1 becomes T0 (T-zero). T0 is just the amino acid backbone(called "tyrosine") with no iodine atoms attached. Because it has no attached iodine atoms, T0 is no more a hormone than is T4.

Rather than being a hormone, T4 is a “prohormone.” That means that enzymes have to convert T4 to T3 before T4 benefits us. T4 is no more a hormone than beans in an unopened can are a food. For all practical purposes, canned beans become food only when a can opener frees them so you can eat them. Hence, T4, like canned beans, only potentially benefits us, but actually does so only after being freed from its metabolically unusable form.

Your endocrinologist may say that T4 is a gentler way to get T3 into your body. This to me, however, is a specious argument. When taken properly, T3 can effect one as gently as T3 derived from T4".

Dr Lowe's patients took one dose a day of either NDT or T3 and it is T3 which has to saturate our Receptor cells. Excerpt:

And finally, why do I specify that the typical patient use one full dose of non-timed-release Cytomel for life? Because extensive testing has shown that this is safe, effective, and most economical—when used within the context of our entire protocol.

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Thanks for really good info Shaws


This is a link re Thyroid and Heart which should interest you.


Recovering with T3 by Paul Robinson explains how to take T3 safely. It is very important to go slowly and leave a couple of weeks between each slight increase.


Monitor before and after doses if you want to be really sure about how u r responding to t3. Theme, heart rate and blood pressure just before and the same 1-2 hrs following. But get some baseline vitals for a few days first so u know what is normal for u.


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