Since being on T3 (6.25mcg) for 2 months I've noticed that my recent blood test showed my FT3 at 3.9 (4.0 - 6.8). Still under-range. Before when I was on Levo only it was 3.7. Not a big increase. As the recent blood test was taken over 24 hours after my last meds could this small increase in FT3 be the result of the T3 having left my body after such a long gap?

I am now taking 10mcg of Lyothyronine split into two doses and 62.25mcg of Levo and based on the above results I can't see my FT3 levels rising very much. Would it be too much to add another 5mcg in two weeks time or wait until the next blood test which won't be until October. Incidentally, my FT4 is 17.3 (12.0 - 22.0) TSH 0.67 (0.27 - 4.20).

Just out of curiosity which is the stronger Tiromel or Lyothyronine? Thank you for your response.

12 Replies

  • Mischa, I'd increase Liothyronine by 10mcg or Tiromel by 12.5mcg. I find Liothyronine and Tiromel mcg for mcg equally potent.

  • Thank you Clutter: I'm trying to understand why my FT3 levels don't seem to rise much. Having been on 6.24mcg of Tiromel I've recently started 10mcg of Liothyronine but am wondering if it will raise the FT3 much. It seems to me it will just about reach the lower range.

    Would it be possible to add an extra 5mcg in a couple of weeks time in order to bring the level up?

  • Mischa, was the blood test when you were on T4+6.25mcg T3 or when you were on T4+16.25mcg T3?

  • Thanks for getting back Clutter: The recent blood test was on T4 + 6.25mcg of T3. I've only recently starting taking 10mcg of T3 and the same amount of T4.

  • Mischa, I still think you can increase to 10mcg Liothyronine in 2 weeks.

  • Your T3 wouldn't have left your body in 24 hours. It has an 8 hour half life.

  • Thank you Muffy. Trying to understand my low levels of FT3.

  • Mischa, it's low because you aren't on enough T4+T3.

  • Clutter: Okay it makes sense. One more point does the addition of T3 suppress T4? Thank you for you quick response.

  • Mischa, T3 can make T4 lower as less T4 needs to be stored for conversion and T3 can stimulate better conversion.

  • Very grateful Clutter for your comments. Makes me feel more confident on where to go.

  • Did you have your blood drawn at the same time of day as you did the last one, as that could make a difference to your readings?

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