FT3 ups and downs in T3 therapy

This is not really a post. I have translated Tania Sona Smith’s article, https://thyroidpatients.ca/2019/11/25/free-t3-peaks-and-valleys-in-t3-and-ndt-therapy/ , into Norwegian.  For every Norwegian page, I want there to be a corresponding English, and vice versa.  

This is just a presentation of Tania’s piece. She is looking into the reseach on how Ft3 behaves after dosing with T3 containing medicine.  Actually, there is not really any good studies on the subject . There is a study on FT3 after a single dose of T3. But that is not what most people take when dosing with T3. We do multidoses. There is no study on FT3 when multidosing, but there is one on T3, that is total T3. Where I live in Denmark, we cannot have FT3 tested. The endoes have forbidden it, they claim, FT3 fluctuates too much, it cannot be trusted. How do they know? With no studies? Anyway, FT3 and T3 follow each other in most instances . With a very important exception, when we take estrogen orally. Then both T4 and T3 becomes higher and FT4 and FT3 lower. So  VERY important to have the frees tested.

Anyway, there is a study on multidosing and T3, showing that T3 peaks app 2 hours after intake. So pretty unstable. Except of course, the peaking is very easy to predict. At least for us patients. I don’t know if the Danish endos,( and the English) have heard about the single dose experiment (Jonklaas et al, 2015) maybe, where one sees a huge peak after intake of 50 mcg T3 in one go. If that is the fluctuation that has scared the shit out of them. And then they never got around to reading  Busnardo et al’s study(1980) on total T3 and multidosing. Even though that study has been around for 40 years. 

Tania goes into all this and more.  We really need a good study on the FT3 level through the day and night. Preferably for all three T3 containing meds, Mono T3, synthethic T4/T3 and NDT.  And with differing dosingregimes. We are many today who also take a dose of T3 at bedtime, others set the alarm 2 hours before getting up, to provide T3 for the cortisolproduction that takes place in the early morning.  Considering how FT3 probably peaks 2 hours afterdose, that is maybe not the best time to take it. Anyway, such a study would be great.


  1. Michael

    The solution is obvious to the T3 conundrum of a short half-life. Do b.i.d.

    • Liv

      Hi Michael!
      Yes, for most people dosing twice a day is absolutely necessary. Many dose 3 times or more. I swear by a dose as I go to bed. Taking only one morning dose is a very bad idea, as one then will have one’s lowest levels in the late night/early morning. When our cortisol is being produced. I know people who take their whole dose as they go to bed.

      Blessings, Liv

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