Thyroid UK
85,563 members100,498 posts

Adding T4 to T3?

Hi everyone. My blood test results show that on T3 only regimen my FT4 levels are low (twice below normal range) , but my FT3 is now twice the upper limit. My doctor suggested I should take T4 now together with T3.

Have you had any experience of this? Would it mean my Reverse T3 will increase if I add T4? Or is it a good idea to take it if my T4 is low?

They do not test for RT3, by the way, here :(

12 Replies
oldestnewest

If you take T3 only, a low T4 is to be expected because our body isn't producing any and you aren't taking any.

The blood tests were introduced along with levothyroxine (T4 only). Before that we were given NDT according to our clinical symptoms - no blood tests then.

NDT contained all of the hormones our healthy gland would have produced, so blood tests are only a guide regarding levothyroxine. TSH is used to diagnose us and ignore any clinical symptoms we may have.

I take T3 only and have nothing but praise for it as I am fit and well and symptom-free. Reverse T3 only happens if you take levothyroxine.

How long did you leave, after taking T3, before having your blood test?

Levothyroxine, T4, is inactive and it's job is to convert to T3. T3 is the Active hormone required in every receptor cell in our body.

Did

3 likes
Reply

Depends how well your body uses T4. Depends how much he suggests taking. Have you already tried T4? How did you get on with it?

1 like
Reply

Thank you so much for all your replies! I never took T4 before, it was at a normal level, but my RT3 was high and T3 low, so a previous doctor, in a different country, suggested T3 only.

Reply

I don't understand why you would need to take T4, because the whole point of taking T4 is so that it is converted to T3. Can someone explain this? Why would a doctor care if the T4 is low if there is enough T3?

Reply

Inana,

A UK doctor trained to interpret results for patients using Levothyroxine would be concerned about low FT4. UK doctors are not trained to use T3 or NDT so don't understand that FT4 will be low on T3 only.

2 likes
Reply

Thanks for replying. It's so strange though, because if the doctor just paused and used his logic, he would see that prescribing T4 for the sake of raising T4 levels is counter-intuitive.

By the way, I think Swiss doctors are trained the same.

Reply

Yuliyam,

How long did you leave between last T3 dose and blood draw?

1 like
Reply

Thank you for your question. About 6 hours

Reply

Yuliyam,

You are overmedicated to have FT3 twice over range 6 hours after last dose and should reduce dose. FT4 is low because you are taking T3 only. If you add Levothyroxine to the reduced T3 dose you should further reduce T3 by 10mcg for every 25mcg Levothyroxine added.

If you've been taking T3 only for some time you won't have high rT3. High rT3 is caused by unconverted T4. Adding some Levothyroxine to T3 is unlikely to cause high rT3.

1 like
Reply

Thank you so much for your advice xxx I will follow it

Reply

RT3 can happen with T4 only but also with NDT with T4 and T3 presumably..?

Reply

Yes, thia ia my assumption also..

Reply

You may also like...