One thing you NEED to know if you have high Reverse T3

When I work with patients with high reverse T3, they often ask me, ‘so if Reverse T3 doesn’t do anything, why do we even make it?’ And it’s a great question. As far as we know, Reverse T3 has no biological activity and it is considered an inactive metabolite of thyroid hormone metabolism. Let me tell you though, Reverse T3 does have a very important role, and I’ll explain it in just a moment. 

But first, let’s remember where reverse T3 comes from. When we make T4 in the thyroid or take medications containing T4, we convert some of it to its active form (T3) and another portion becomes Reverse T3. In fact, chemically, the difference between T3 and Reverse T3 is minor:

—> T3 is essentially a T4 molecule that has had an iodine atom removed from its OUTER ring.

—> Meanwhile, Reverse T3 is derived from a T4 molecule that has had an iodine atom removed from its INNER ring. 

And therein lies the difference as to whether it will be biologically active (aka, T3) or not (Reverse T3). 

But this brings me back to our original question of WHY do we make reverse T3 if it has no known biological role? The answer is simple: It gives us an ‘off switch’. 

If we think of the thyroid as the motor of the body, setting the pace of all the processes and systems that keep us alive, T3 is like the accelerator, while reverse T3 is the brake. The more T3 we have, the faster the body’s system. The more Reverse T3 we make, the more we’re slowing things down. 

We would never design a car without a brake, and similarly, the thyroid has an in-built system to help slow things down when conditions aren’t favourable. That system is the ability to convert our thyroid hormone into Reverse T3. It gives us an ‘out’, if things are getting too fast.

So what do I mean by conditions that aren’t favourable? Well, for example, we know Reverse T3 increases during prolonged fasting, pregnancy, caloric restriction, chronic illness, inflammation and during times of stress. Why? To conserve energy! To slow the body’s motor and take the foot off the peddle, so to speak. T4 always needs to be converted into something, so being able to ‘shunt’ towards reverse T3 (and consequently, away from T3) allows the body to apply the brake and conserve energy and resources during these metabolically stressful times. 

So finally, this brings us to the question of what to do if your Reverse T3 is high? Well, you need to understand that your body is trying to put the brakes on and you need to ask why. Is it chronic stress or persistent, low grade inflammation? Could it be dietary factors, such as nutritional deficiencies, dysglycaemia, very low carbohydrate diets, prolonged fasting or caloric restriction? Is it related to impaired liver function or perhaps a combination of factors? Whenever we are shunting to Reverse T3, we have to ask WHY? That is the key to addressing the root cause of the issue and rectifying your reverse T3 issues for good. And this is why I spend so much of my time working with my patients to understand the root cause of their thyroid issues - because we have to work from the ground up to build the right foundation for thyroid health and wellbeing longterm! 

Niki x