How long for TSH to stabilize after stopping T3 medication?

[TurtlesAllTheWay]

I know the guidelines are to test 6-8 weeks after any med change but I'm wondering, could TSH levels stabilize more quickly from changing T3 medication alone?

In my case specifically, I was on levothyroxine only for about 3 years for hashimoto's, then over the past 4 months or so I self-medicated adding gradually increased doses (5-25mcg) of T3. I became slightly over-medicated and decided to discontinue the T3 for a while. I did taper down over a few days but stopped pretty abruptly, continuing the same dose of levothyroxine. It's been about a week off T3 completely.

Any ideas how quickly TSH might come up? It was suppressed by the T3 meds for a couple of months. Thanks!

[helvella Administrator Thyroid UK]

Even if TSH did stabilise more quickly, how could you know?

Let's consider someone who changes their dosing and re-tests after 2, 4 and 6 weeks.

I suggest that for many, there will be an obvious change at 2, and a smaller change at 4. But even then, you have no idea if 6 will be indistinguishable from 4, or not. It is only when you test at 6 you find that out.

TSH usually only changes by small amounts each day. Otherwise, one odd day (on which you needed more, or less, thyroid hormone) would see significant changes in TSH. It would be over-sensitive and result in excess swings in thyroid hormone levels.

(Have you ever seen a speedometer in a car when the needle is undamped? It wobbles up and down far too far and far too fast. You can never read it until the car stops and it shows zero!)

So it inevitably takes time for TSH to change significantly.

And, whatever that change is, it could either overshoot and then drop back. Or move very slowly.

You simply cannot expect everything to change to another stable point quickly.

6 to 8 weeks is a best guess. There is nothing magic about that time. Things start to change very quickly.

[willow80]

Dear EntopyE

I have never tried T3 being on T4 for well over 30 years. I did check with my GP though and she stated that I didn’t require T3.

On investigation the TSH will take 4-6 weeks to be back to how it was previously, however it will be added as a drip feed each day.

Do hope this helps.