Research Shows T4 is Not Needed in The Brain of Adult Thyroid Patients

This is a blog post that finally proves that thyroid patients do NOT need to take some T4 medication in order to make their brain function properly!

I have been told too many times that there is research that shows that our brain and central nervous system can only use T4. I have always known that this view is incorrect.

I have always argued that this is not true. There are large numbers of people, just like me, who are fit and healthy on T3 Only.  I have almost zero T4 in my body and I am healthy and can certainly think and have no central nervous system issues!

We also have studies that prove that there are no negative effects from long term use of T3-Only.

Well, to finally draw the curtain closed on this false belief that all thyroid patients should be taking T4 medication there is research now that has proven that adults use T3 in the brain and central nervous system very easily.

The new research is changing the entire understanding of how the body compensates and alters how it operates with thyroid hormones. This research has revealed the discovery of active transporters.

There are active T3 transporters and they are more active in adult life. This mechanism is now known to explain how T3 passes easily into the brain and central nervous system.

So, circulating T3 is a source of T3 for the brain. It is not exclusively dependent on T4.

But this change of belief in transport, rather than diffusion, is relatively new, and more transporters are being discovered.

Other, older assumptions have been proven wrong and more assumptions will be proved wrong in time.

The assumptions had to be wrong anyway, based on actual experience of thyroid patients with T3. This is what I have been saying all along. 

So the people that say we cannot live without some T4 need to now be quiet on this topic.

I have also spoken with thyroid researchers who believe our understanding of how thyroid hormones work within the body may continue to be revised as this area of research reveals more.

Here is the research paper:

“Thyroid Hormone Action: Astrocyte–Neuron Communication”
Beatriz Morte and Juan Bernal
Front Endocrinol (Lausanne). 2014; 5: 82.
Published online 2014 May 30. Prepublished online 2014 Apr 22. doi:  10.3389/fendo.2014.00082

Best wishes,


Paul Robinson

Paul Robinson is a British author and thyroid patient advocate. The focus of his books and work is on helping patients recover from hypothyroidism. Paul has accumulated a wealth of knowledge on thyroid and adrenal dysfunction and their treatment. His three books cover all of this.

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