Question:

[Bright-eyes]

Question: If I take 112mcg of T4 then add 10mgs of T3 what would my equivalent total dose of T4 be?

[helvella Administrator Thyroid UK]

There really isn't an equivalent. Far too much about this sort of thing depends on you. We are all different.

You will find lots of people claiming 3, 4, 5 even ten-fold effect from T3 rather than T4. So that could be an extra 30, 40, 50 or 100 micrograms. And every one of these is just a guess.

I've tried to explain why this is the case in my blog. Not a quick and easy read, I'm afraid.

helvella - How much more potent is T3?

A discussion about the relative potency of T4 and T3.

helvella.blogspot.com/p/hel...

[Bright-eyes in reply to helvella]

Thanks Helvella, I’ll have a read.

Can I also ask should T4 be at the top of range to feel better? And if T3 lowers T4 how can we ever know what our correct range is?

[helvella Administrator Thyroid UK in reply to Bright-eyes]

Our correct levels are where we feel best. Not a number. Not a point on a range.

We can observe that most people seem to need FT4 somewhere towards the top of the range (maybe in the top quarter) to feel well when they are ONLY taking levothyroxine. But they don't have to make it hit the top of the range. If you are good at 75%, then that is good for YOU.

Adding T3 makes the arithmetic more complex but the idea is the same. If you are doing very well, then that is good. If you are not doing well, you can look at the numbers and see if they suggest something might need to change.

If you were doing well, and now are not, then comparing where you are now with when you were well can help suggest what to do.

When people add T3, they all too often reduce their levothyroxine. But that isn't necessarily the right thing to do. And quite a few start on the lowest dose they can manage to achieve - typically 5 or 2.5 (by splitting). Then see how that goes, and increase the T3 as and when it seems right.

[radd]

Bright-eyes

T3 up-regulates certain enzymes meaning you get more than the amount you medicated. This is one of several reasons why people may be sensitive to it.

Most basic calculations are done on a 3:1 or 4:1 basis. Therefore, 112 + 30 = 142mcg T4 or 112 + 40 = 152mcg T4

[Bright-eyes in reply to radd]

Thankyou for posting this helpful information Radd.