The Hypothalamus-Pituitary-Adrenal-Thyroid (HPAT) Axis - Hormone Connections

The Hypothalamus-Pituitary-Adrenal-Thyroid (HPAT) Axis - connections between hormones

The Hypothalamus-Pituitary-Adrenal-Thyroid (HPAT) Axis – thanks to Fullscript for this infographic!

I talk a lot about cortisol, but it doesn’t exist as a lonely hormone. If you look closely, you can see that the thyroid (see TSH, T4, T3 and rT3) and adrenal glands (ACTH, cortisol) are tightly connected. The (+) and (-) icons indicate positive and negative feedback throughout this entire axis – how fascinating!

So, for example – you can see that there is negative feedback from cortisol —>  the conversion of T4 to T3. T4 is inactive, and T3 is active.


The verdict? Cortisol can directly prevent the conversion of T4 to T3, which works against optimal thyroid function. Note: managing the thyroid also means moderating cortisol.


This HPAT axis can be affected both positively and negatively via numerous factors, some being:

  • Sleep habits

  • Stress (physical, mental)

  • Medications and Natural Health Products

  • Gut dysbiosis

  • Blood sugar imbalance

  • Autoimmune disease

  • Hormones (birth control, hormone replacement therapy)


And this is just a TINY piece of the puzzle. If you Google ‘steroid pathways,’ you’ll see for yourself just how complex the hormone puzzle is!

Interested in reading more?