Why would SMALL increase in T3 meds have caused fT3 to go DOWN a LOT and fT4 to also go DOWN?

[Joyya]

Can someone help explain the mechanism? Given all nutrients of importance are optimal, why would a very slight increase in cytomel from 10 mcg to 12.5mcg, keeping Synthroid the same (at 75 mcg) have caused

— fT3 to have dropped significantly from 65.6% to 37.5% of the reference range (from Oct 24 2022 to April 27, 2023)

—fT4 to have dropped from 41.76% of the reference range to 34.07% of the reference range (from Oct 24 2022 to April 27, 2023)??

The MD put my Cytomel back to 10mcg and increased Synthroid to 88 mcg. This seems like the right way to go (and I am feeling much better) but I can't understand why that small increase in cytomel caused fT3 to drop SO much, as well as fT4 to have dropped.

Thanks.

Here are the actual labs numbers with ranges.

April 27, 2023

—Thyroid Stimulating Hormone (TSH)

0.02 (0.32-5.04 pmol/L)

—Thyroxine fT4 : 14. 4 (10.6-19.7 pmol/L) - 34.07% of the reference range

—Triiodothyronine (T3) Free 3.8 (2.6-5.8 pmol/L) - 37.5% of the reference range

October 24,2022

—Thyroid Stimulating Hormone (TSH)

0.10 ( 0.32-5.04 pmol/L)

—Thyroxine FT4 : 14. 4 (10.6-19.7 pmol/L) — 41.76% of Reference Range

—Triiodothyronine (T3) Free 4.7 (2.6-5.8 pmol/L) — 65.5% of Reference Range

[SlowDragon Administrator]

TSH low in October, but not as low as on higher dose

Looking at your profile you test negative for TPO antibodies

Have you had Thyroglobulin antibodies tested yet

[Joyya in reply to SlowDragon]

Yes, thanks. Tg-Ab were 14 (< 40 IU/L)

I am also eating gluten free since those results (if that matters).

I can't figure out why fT3 would drop so significantly given I was on a slightly higher dose of cytomel (and fT4 dropped, too). No brand change. Both were brand name (not generics).

[TiggerMe]

My interpretation would be...

Is it that more of your T3 receptors have been re-awoken and are drawing it from your blood and into use in your cells which in turn makes you feel better and maybe do more.... which is also drawing more from you blood to your cells?

The sign that you feel better shows a better uptake and it is getting where it needs to be rather than just circulating in your blood?

[hipolion]

yes, I noticed that too! The more I take t3 in the morning, the values decrease, my tendons hurt, my skin gets dry, my stomach swells, as if I'm going into hypo,...etc.

So I decided to divide the dose into 3, no more than 5 mcg at a time and the values are stable.

[Joyya in reply to hipolion]

Thanks, but my dose was divided into three.

[hipolion in reply to Joyya]

you didn't specify that and how do you divide 12.5 into three?

[Joyya in reply to hipolion]

I am no longer doing that as my dosage has changed, but used a Xacto knife and a cutting mat.

I am trying to under why the suppression of fT3 and fT4 with only a 2.5mcg increase in cytomel (over divided doses).

[BonnieG123]

I have been on synthroid for over 25 years. In the beginning there was a bit of trouble adjusting the dosage and back then we never were given the results just told about them. I go for my regular checkups every six months we discuss any symptoms or problems and I’m on my way. It’s up to me to eat healthy (which I don’t but have started a program to help me do that) and I’m on my way. Back before the correct dosage was established it was constantly tweaked by small amounts indicating that small amounts make changes in the same way that one glass of wine makes changes that are different from two glasses of wine. It’s a comfort zone. You know when you’ve achieved it. I know this doesn’t answer your concerns but I hope it helps in some little way.

[Hidden]

What was your TSH before?

[Joyya in reply to Hidden]

As outlined above, October 24 2022 Thyroid Stimulating Hormone (TSH) was 0.10 ( 0.32-5.04 pmol/L)