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Thyroid UK
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Test results advice please

Latest results on 100 t4 and 18.75 t3.

Tsh <0.03

Ft4 17.9 (10-19.8)

Ft3 5.7 (3.5-6.5)

6 Weeks ago I decreased t4 by 12.5 and increased t3 by 6.25.

Results on previous dose (112,5 t4 12.5 t3) was

Tsh <0.03

Ft4 20.3 (12-22 )

Ft3 5.9 (3.1-6.8 )

I want feeling well att all in that dose and since swapping some t4 for t3 I am feeling much better but a feel that there is room for improvement. Do I need my t4 as high as 80% in range or does it make sense to decrease this further? How much t3 can I add if I decrease t4 by 25?

Option 1 would be:

Decrease t4 to 75 and add more t3 either 6.25 or 12.5

Option 2:

Keep t4 a it is and increase t3 by 6.25.

What do you think?

4 Replies


It's difficult and very individual so we have to keep tweaking until we find the right levels where we feel best.

My results were similar to your current ones and I reduced Levo by 25mcg, my FT4 plummeted to almost bottom of range, much to my surprise, and made me feel very unwell. I had to increase it back by 25mcg and FT4 has never reached the same level again.

Then I had to change brands of T3 and found a difference in strength so again had to find what was best for me.

Only you know how you feel so only you can say where you need FT4 to be, same with FT3. It's a PITA but tweaking doses is the only way you'll find out where you feel best.

1 like

Thank you! Do you think it could push my ft3 over range if I intresse by 6.25? Either way I do it (decrease t4 and add 12.5 t3 or just add 6.25 T3) I would get an increase in t3.

Was your ft4 ok when you were on 75 t4 when you started t4. I mean usually we start low and invest by 25 so I have been on 75 t4 and then my levels were middle of range. Did you also have ok levels?



It's over 40 years since I started on Levo and I can't remember anything about it. There was no help around then, doctors didn't discuss test results and dose changes and I was too young to think about asking.

Adding 6.25mcg T3 might bring you to the top of the range. If it was me I would try that first, leaving Levo at the current dose. See how you feel and retest in 6-8 weeks.


Thank you so much for your advice. 😊


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