Can anyone convert dose of t3 to t4?

[Dee8686]

Just out of curiosity and as I can’t get in touch with my endo as he’s away at the moment. I’m now taking t3 only which I’ve just started. Does anyone know how to convert to equivalent t4 please?

[Aurealis]

There are different conversion rates used. For example 100meg Levothyroxine / T4 equivalent to 20mcg Liothyronine /T3

[Dee8686 in reply to Aurealis]

Ok so t4 is 5x t3 dose?

[Aurealis in reply to Dee8686]

Yes, but as I said, there are different conversion rates out there. This has worked for me.

[Angel_of_the_North in reply to Dee8686]

No. more like 3 x. The studies that say 5 x are mostly the ones that were set up to prove that T3 doesn't work by giving too low a dose compare with the dose of levo.

[helvella Administrator Thyroid UK in reply to Angel_of_the_North]

In a healthy human being, approximately one third of the T4 their thyroid produces gets converted to T3.

If that ratio were to be the same in someone on T4 monotherapy, then a 3x factor would make sense at the simplistic level.

[humanbean]

I always divide T4/Levo by 3 to get the equivalent T3 dose. So to go the other way, multiply by 3.

So, 25mcg T3 is roughly equivalent to 75mcg Levo.

I think the reason for the differences between people is because they have different rates of success in absorbing tablets and medicines of all kinds.

[SeasideSusie Remembering]

I've seen 3x, 4x and 5x

I tend to go for "approx 3-4 times so 25mcg T3 is approx 75-100mcg Levo"

[greygoose]

It really depends how well you're capable of converting T4 to T3, and everyone is different. But, as a rough ballpark, I would agree with Susie - T3 is 3-4 times 'stronger' that T4.

[eoram25]

I don’t have a thyroid. I was on 130mcg T4; I’m finally feeling good with no symptoms overstimulation on 80 mcg T3 in three divided doses. You have to go by symptoms