The important role of Reverse T3, and when it goes wrong

During the process of converting the inactive T4 hormones to the active T3 hormones, the body converts some of this T4 into another hormone called Reverse T3.

Reverse T3 (shortened to rT3) plays an important role.  It acts like a balancer – to make sure that there is not too much T4 going around in your body.   But like Goldilocks in the fable, we want just the right amount of rT3.  

Too much rT3 can create problems.  Research has shown that rT3 acts like a T3 blocker.  So if rT3 levels are too high, then the active T3 cannot get into the cells.  

rT3 can also slow your metabolism, which is important in the event of starvation, serious illness or high stress.   So in these circumstances, your body will convert more T4 into rT3 (and not into the active T3). 

So, if you are concerned that your T3 is not getting into your cells, you could have high rT3 levels.  But the only way to know for sure, is to have your blood drawn and tested.