Thyroid UK

How quickly does the TSH respond to a reduction in T3?

Is 7-10 days long enough to see a rise in TSH?

I ran out of T3 and am now feeling like death even though I'm on 100mcgs levo as well.

I haven't taken my T3 for over a week ( 15 mcgs a day) .

I got bloods done today and thought perhaps my TSH would have risen but it hasn't?

Also do I now have to build my T3 up again slowly after a 7-10 day break?

I know I'm stupid so don't shout.

4 Replies

TSH responds quickly to a change in fT3 or fT4. However, since T4 hangs around a lot longer than T3 TSH it takes longer for fT4 to fall and TSH to rise. The other consideration, a big one, is that if TSH has been suppressed for some time it might take quite some time for the pituitary (the thyrotrope, the bit that produces TSH) to pick up again and sometimes it doesn't fully recover. So, if your TSH was suppressed it might take a few weeks to pick up. Also 15 mcg L-T3 will not have a massive effect on TSH.


thanks Jim.

Can I Pm you?




I've PM'd you.


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