Log in
Thyroid UK
93,494 members107,554 posts

Switching t4-only to t3-only, t3-only to NDT-only, and then to NDT + t3-only

Hi everyone,

I stopped 0,38mcg T4-only medication (tirosint), I could not tolerate even such low doze.

On the last day of t4-only I tested my blood.

TSH 3,05 (0,27 - 4,20) high

FT4 20,33 (11,60 - 21,90) high

FT3 3,96 (3,08 - 6,78) low

Thyroid peroxid. 177 (<34) higher than before

RT3 test result came a month later (see below).

My integral doctor recommended 1 grain NDT, buildup step by step. But first I was without any T4 or other meds for 12 days while waiting for NDT. Started to get extremely hypo, couldn’t wait for NDT, started low dose T3-only (cytomel).

I used 7,5 mg per day (2,5mg x 3per day). That week on low T3 dosage was actually showing the highest promis that I can feel myself good someday.

When I got on NDT, I stuck at raising my dose to 3/4 of a grain (27mg t4 + 6mg t3) . And here I got the result of my rt3:

RT3 304,9 (138,6 - 331,1)

Rt3 ratio 13 (>20)

Clearly ratio needs to be balanced out.

When I was switching to NDT from T3, did I do smth wrong? The doctor said Cytomel half life is 4 days, and I had to wait all 4 days without any of it to begin with NDT. Then to add 1/4 of NDT every 4-7 days.

I could not survive without t3 even a day. So I stopped Cytomel. The next day I started NDT 1/4 grain, after 2 days I added another 1/4 in the afternoon. After 7 days 1 more pill... and here I felt worse.

Could it be effect of RT3 building up, or I just got too fast with building T4 up?

Anyway I got the decision to go down to 1/2 grain of NDT and add t3 to it. But how much of t3 will be safe? Do I need to build it up gradually? Up to what dose then? Should I stop NDT completely or temporary or not to stop?

Yesterday I had two dosages:

8 am 1/4 NDT + 2,5 mg Cytomel

4 pm 1/4 NDT

Around 2 pm I already felt very bad, and 8 pm I was a total mess.

Please, any advice would be interesting to hear!

P.S. Can not reach my doctor. On Monday planning to draw blood to see TSH, FT3, FT4, total T3, and some vitamins.

I am so bound to home. And in a week we are going on a trip to Spain. That will be a challenge...

2 Replies


If your rT3 blood test was drawn when you were taking Tirosint, rT3 which wasn't high and was within range, will have dropped as you were off meds for 12 days. rT3 ratio is not a guide to health. Read tiredthyroid.com/rt3-3.html

I think it was poor advice to tell you to stop meds for 12 days before starting NDT to stop T3 for 4 days before starting NDT. This can only have made you more hypothyroid.

You seem to have been stopping and starting different meds at different doses frequently and this won't help your metabolism stabilise.

How long were you taking 3/4 grain NDT?

Why did you switch to 1/2 grain NDT plus 2.5mcg Cytomel? There is 2.25mcg T3 in each 1/4 grain NDT.

Unless you've been on a stable dose for 6 weeks I think your test will be a waste of money and you would do better to wait.


Thank you for your answer Clutter.

The decision to stop tirosint was my own, I just felt like my throat could explode like a bomb any moment, extreme pain, fatigue, blood spotting, could not stand tirosint any longer. Before it, I was also on 50 mcg tirosint for a couple of months, my FT4 was above ref range then, and I felt worse than now.

It is good to know that at least I did not make a mistake by not stopping T3 for 4 days before starting NDT.

I am on day 17 today with NDT in general, 3/4 grain - 9th day. Yesterday I started to add Cytomel.

According to this article, you referred to, I belong to Profile 2. They also recommend to address high cortisol or low iron, I posted my iron test results in my previous post. Looks like not optimal, and I am going to supplement it. Would you be so kind and look into it for me? It's interesting to know the opinion of others. I feel like I am left pretty much on mine own and am scared that I will harm myself with such experiments.

I lowered the dose of NDT, because with every day felt worse, clearly because of that T4 in NDT. After taking Cytomel it almost immediately gives me such an improvement, but I am still catastrophically sleepy most of the time, and getting pain in the kidney areas... 4 hours after taking meds all bad symptoms come back. 2,5 mcg of T3 work only 4 hours for me. Is it with everybody so short? If I raise my dose tomorrow again, is it not to fast? I added one more t3, so today my dose is 1/2 NDT + 5 mcg T3.

I 've read a comment of Shazbrett, her tests look a little bit like mine, just her RT3 is higher than range. But the RT3 ratio is also lower. You recommended her to stop t4 for some time and start t3-only for some time.


That is when I started to think that I might benefit if I at least reduce my dose of NDT. I am so afraid of the moment which is described on different websites, that if you stop it, then raise T3-only, and when RT3 is flushed out you may get overdose with T3 overnight.

That is why maybe taking a small dose of NDT is sort of preventing such rough transition?

On the other hand - My body rejects T4, t4 is transferred to too much rt3, Cytomel helps to keep rt3/ft3 ratio normal (above 20 in my case). But if I would not get additional t4 my rt3 would be closer to the middle of the range, right? And my dose of t3 would be lower too...

So maybe there is sense to stop NDT?


You may also like...