Reverse T3 and CT3M

[Paul Robinson]

FT3 is far more useful than total T3. Knowing how much T3 exists in a form bound to protein is nearly completely useless information. It doesn't do anything other than tell you that there is T3 there. It is entirely inactive. I would never look at total T3.

[Anisa]

FT3 is far more useful than total T3. Knowing how much T3 exists in a form bound to protein is nearly completely useless information. It doesn't do anything other than tell you that there is T3 there. It is entirely inactive. I would never look at total T3.

I totally agree!

With one exception: the method of calculating the ratio between T3 and RT3. One can not calculate between different units of measurement. In order to calculate the ratio between two hormones, in principle, they should both be present in the same unit of measurement. Either "free" to "free" or "total" to "total". Because RT3 is available only as total measure, we need a total measure of both - RT3 and T3 - to calculate the proper ratio between these two. Ratio calculated between the free value of T3 and total value of RT3 can not be entirely correct.

Really interesting lecture about exactly the role RT3 plays in thyroid conditions Optimizing Thyroid Function - A Look at Reverse T3 -- The "Brake Pedal" of Our Metabolism.

[Paul Robinson]

Yes - but I also re-state that there is no ideal FT3/rT3 ratio at all.

People vary and sometimes someone can be well with a quite high rT3 and sometimes it needs to be very low.

Also, rT3 is highly volatile and fluctuates greatly in the day. So, a blood test at one time may show a high rT3 whereas one hour later it may be a lot lower.

I think rT3 is an important hormone but the FT3/rT3 ratio isn't important. Only very high rT3 numbers are usually helpful.

Symptoms and signs is most often the best way to assess actual thyroid hormone activity. Symptoms like energy level, weight gain/loss, whether someone feels warm or whether they are constipated or not, and signs level actual body temperature tell us more about our thyroid hormone activity than most blood tests do.

[Anisa]

Thanks for your comment.

Only very high rT3 numbers are usually helpful.

Yes, but how can one know how high this ratio is, in fact, if this ratio is not calculated correctly?

I understand your point very well, but I do not comment on the opinion about whather one can or can not use the ratio between T3 and RT3 for anything.

My only issue here is that in order to be sure of a correct result, both components must be present in the same unit of measurement, which in this case is a total value of T3 because the value of RT3 is already given in a total amount. If anyone wants or needs to know its own T3/rT3 ratio, it is necessary to obtain blood test to determine the total value of T3. Otherwise it's meaningless.

[Elbeth]

Really interesting lecture about exactly the role RT3 plays in thyroid conditions Optimizing Thyroid Function - A Look at Reverse T3 -- The "Brake Pedal" of Our Metabolism.

The link to the lecture on YouTube dosn't work any more. The YouTube account linked to the video is cancelled.

[Paul Robinson]

I assume you have to convert them into equivalent units. Since they are both measures of the amount of a hormone present in a volume then there should be a way of converting them.

Since I never use these ratios at all then I don't have the specific answer. FT3/rT3 and total T3/rT3 are both regularly looked at by some doctors and so they must be able to convert the units.

I just don't know the maths because I don't use the ratios as I think they are generally unhelpful.

Paul