Does thyroxine alone control T4 levels?

As mentioned before, I am currently trying out taking both T3 and T4.

I felt best on 100mcg T4 and 20mcg T3, but endo says my TSH is too suppressed at 0.03, so he thinks I am over medicated.

Have since tried 50mcg T4 and 30mcg T3 per day but didn't feel right on that, so am now on the final option of 100mcg T4 and 10mcg T3.

My last test gave an FT4 result of 9.8 which I thought seemed on the low side, but he didn't seem at all concerned - only figure he cared about was the TSH. I know that the parameters changed for FT4, can anyone tell me what they are now please.

Also, is it possible that changing thyroid medication could have an impact on breasts? I have been getting some breast pain lately!

15 Replies

  • Not sure about the breast pain....

    You need to know your own reference ranges for your lab I'm afraid. FT4 DOES look a bit low, but without your ranges it is hard to tell....

    Some people need a supressed TSH to feel well, there is also evidence coming out soon to show that the TSH is nonsense as there should be different parameters depending on LOADS of different factors!

    How are you feeling now? What symptoms have gone/returned/never gone..? Did you FEEL over medicated?

    Have you had the Pulse article which says some people need TSH to be low and FT4 to be high..? Email me -



  • Very interesting, Louise. Do you have any more info about the evidence on TSH being nonsense? Sounds like just what we have all been waiting for.

  • Evidence is growing that not only is the paradigm of free T4 being proportional to TSH wrong, but that the TSH "normal" range changes according to circumstances like how big your thyroid gland is, your weight, your age, and many other things like if you are on medication (T4,T3 or both). People on exogenous thyroid do not have the same reference range as normal euthyroids and the effect change is significant.

  • Where did you find this info? Are there any studies we can read, please?

  • All I can ask is for you to be patient! I, Profs Hoermann and Dietrich together with a German hospital providing the patients/data are at this moment working up a big clinical trial which demonstrates these phenomena, for publication asap. And this study implicate corresponding changes in TSH-FT3 relationships as well. Watch this space! Otherwise there is a new reference which deals with some of these findings:

    Triiodothyronine and Free Thyroxine Levels are Differentially Associated with Metabolic Profile and Adiposity-Related Cardiovascular Risk Markers in Euthyroid Middle-Aged Subjects

    Greet L. Roef, Ernst R. Rietzschel, Caroline M. Van Daele, Youri E. Taes, Marc L. De Buyzere, Thierry C. Gillebert, and Jean-Marc Kaufman

    Thyroid, Vol. 24, No. 2, February 2014: 223-231.

  • Kent Holtorf's site

    and all the rest of the site

  • Ta da - see above! :) x

  • Would you send me the link to the Pulse article too please Louise?



  • You will need to email me -



  • T3 suppresses TSH and FT4 and your endo really should know that.

    If you feel well I really wouldn't change your dose. 0.03 TSH is suppressed, but thyCa patients are deliberately suppressed for up to 5 years and don't go around having heart attacks, strokes and fractured bones, so I really don't understand why it is so bad for non-cancer hypo patients.

  • The pituitary takes in both T3 and T4 from the bloodstream. It converts at least some of the T4 into T3 and reacts to the combined effect of the both bloodstream T3 and locally-converted T4.

    Conversion within the pituitary has some special features which means that it is not exactly the same process as elsewhere.


  • Rod - any idea about the cystic breasts/iodine article..? xx

  • I've had breast discomfort at too high levels of T3 but I don't know if this is like you're getting, you may need to get it checked out, or try reducing T3 slightly and see if it goes

  • I know I have read somewhere that there is a connection between cystic breasts and I think low Iodine levels. I'm sure one of the admins would know the article. I think low iodine can result in breast cysts. I was interested because for a number of years before I was diagnosed hypo I was forever having breast cysts drained. Haven't really had any problems since being on levo.

  • Hmm, yet another irritating symptom. I've been getting breast pain too for the first time in my life but I'd be very surprised if my t3 was high as I feel like pants at the mo. Reduced all my meds around Christmas due to being a bit hyper so not likely to be on too much of anything.

    I was on an omega supplement - evening primrose oil - and stopped taking it for a few months, so maybe I should go back to that. I think it is often used to treat breast pain when there's no obvious reason for the pain.

    I have an aunt who had cystic breasts and benefitted from cutting out caffeine.

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