Technical question regarding T4 usage while on T3

[ockerdoc]

I’ve just tested while taking 135mcg T4 and 6.25mcg of T3. Since testing I have come off the T3 due to various issues. I was wondering whether my T4 level would go up or down when not on T3 anymore? My T4 was right at the top of the range while taking the 6.25 T3 but now that I’m off it will more T4 be used up? I am reducing T4 by 50mcg a week but I’m wondering whether I actually should? Thank you.

[DippyDame]

Sorry....results too blurry to read, so cannot comment in any detail

Please type them out with reference ranges.

135mcgT4 + 6.25mcg T3 is /was a fairly large dose

T3 lowers both TSH and FT4 so a 6.25mcg reduction of T3 may in time raise FT4 slightly....or maybe not!

If you were at the top of the ref range with the T3 it's possible your FT4 is now over range which is not advisable

In your shoes I would reduce levo, initially by 25mcg, wait 6 weeks and test again

Why did you add T3.... is your T4 to T3 conversion impaired?

What prompted you to stop it.....did you feel overmedicated?

Too many (big) changes too soon is not going to help

took 6.25 T3 but now that I’m off it will more T4 be used up?

Not quite how it works. By "used up" do you mean converted to T3?

It depends on how robust your conversion rate is and will need time for the hormone levels to first settle

Suggest you get yourself on a stable dose ( probably not your therapeutic dose at this stage) wait 6 weeks then test, the results should then point the way forward....post them.

[ockerdoc in reply to DippyDame]

Thank you 🙏 I took the T3 because I was on a lowish carb diet. Then I got really bad constipation after about 8 weeks on the T3. I thought it was the supplements I take and stopped them but no change. Constipation only went after I stopped the T3 🤷‍♀️ My results were

T4 20.9 (11.9-21.6)

T3 5.77 (3.1-6.8)

TSH 0.075

This test was done after taking 150mcg T4. I was taking 150mcg 5 days and 100mcg 2 days.

I only have 100mcg tablets so I might just reduce 25mcg a week and so 125mcg on 5 days and 150mcg on 2 days then test again. I’ve gone back onto a higher carb diet now so hopefully my conversion will be ok. It has been pretty ok in the past as long as I eat plenty of carbs.