Thyroid UK
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T3 only advice

Until November last year, I was on 75 mcg of T4 and after a blood test, was told to increase to 100 again. Due to never having felt well on T4 for whatever reason, I was reluctant to increase so my doctor suggested it might be worth trying T3 and I am now seeing a consultant who agreed initially to a 3 month trial. She reduced my T4 to 25 mcg and added 10 mcg of T3. Despite being a small dose, I noticed an improvement in my symptoms for a few weeks (mood in particular) then seemed to struggle again. After a blood test in January, my TSH had risen to 11.56 (0.3-5), Free T3 4 (3.1-6.8) and free T4 11.6 (12-22) so a further increase of 10 mcg was added. Again, this helped for a few weeks (much better than when on T4 alone) but then started to feel tired and unable to think clearly again. I explained this to the consultant at my appointment a few weeks ago so she agreed to stopping the T4 altogether (which we had discussed previously) and adding a further 10 mcg T3 therefore now taking 3 x 10 mcg T3 a day and have been told to have a blood test done before my next appointment in 3 months. I started to feel much better again last week and over the weekend (almost 'normal'!) then after a reasonably busy day on Monday, have felt exhausted and not right since. Can anyone advise me as to whether it is just a matter of getting the right dosage in order to feel consistently ok and also if it might be better to take the 30 mcg in a single dose? I appreciate that we are all different and will therefore require different amounts of T3 but I would also be interested to know how much of T3 alone other members are taking and if taking in a single dose or split. Apologies for the lengthy post and hope someone can advise.

2 Replies


10mcg T3 is equivalent to 30mcg Levothyroxine so it was not surprising that you become hypothyroid after your endo reduced dose so much.

30mcg T3 is equivalent to 90mcg which is close to your previous Levothyroxine dose. If you have enough T3 you could try increasing to 40mcg. It is up to you whether you dose once or thrice daily. Try it and see how it suits you. I felt better multi dosing until my FT3 was good because before that I could feel T3 wearing off after a dose.

1 like

Thanks for your reply. I only have enough T3 for 30 mcg daily so perhaps I'll try taking it in one single dose to see if that helps.


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