Low Cortisol or Hypocortisolism or Adrenal Fatigue?

I got asked a question today from a patient who wondered if the adrenals would recover from adrenal fatigue over time or need adrenal cortex support or with some other means of supporting the adrenals.

I have been asked this a lot and this time I have taken the core of my answer and put it here in a blog post:

I do not believe in the idea that adrenals get weak, or sick, or damaged unless someone has an autoimmune disease that is attacking their adrenal glands, or a tumour or an accident that damages them. This can be tested using a Synacthen Test (ACTH Stimulation Test). Most thyroid patients pass this test very easily – because there is nothing wrong with their adrenal glands.

I do not believe in Adrenal Fatigue any longer. I have worked too much with thyroid researchers over the last few years and it has changed my views in this area.

I never use the term Adrenal Fatigue now. I use hypocortisolism or just low cortisol.

Let me be clear, YES, of course, low cortisol is a massive problem for many thyroid patients. This is NOT in question – it is just the cause of it that I am discussing. The terminology also needs to be clearer.

My books have ALL been updated to reflect this view.

The adrenal glands are incredibly simple organs. They keep making cortisol in as much quantity as someone needs, as long as there is enough ACTH (the stimulating signal from the pituitary) and enough cholesterol in the bloodstream. They just can go on and on. This is often why people with Cushing’s syndrome (incredibly high cortisol), keep having high cortisol for years until they are diagnosed. Adding extra pregnenolone or some other supplement is usually not going to make any difference to cortisol levels as all the adrenals require is enough cholesterol and a decent level of ACTH stimulation.

The main cause for non-Addison’s hypocortisolism (low cortisol) is hypothalamic-pituitary axis dysfunction – often of unknown origin, but sometimes because of low FT3.

The pituitary produces ACTH. It is the main signal to stimulate the adrenals to make cortisol, Dhea and to some much lower extent aldosterone.

The pituitary converts T4 to T3 very efficiently within its own cells, if it makes the D2 deiodinase enzymes correctly. Gene defects with D2 (the DIO2 defect), can wreck this conversion.

The pituitary has been discovered to have the highest concentration of FT3 out of all the different tissue types in the body. It needs high FT3.

Thyroid patients who do not have enough FT3 will not be giving their pituitary the help it needs.

Daytime dosing of thyroid meds often leads to low nighttime FT3 levels. 

Some people also have poor conversion – leading to low FT3 levels. 

Any DIO2 gene defect will also contribute to lower pituitary FT3 than it was supposed to have.

Loss of thyroid tissue, through Hashimoto’s or thyroidectomy also loses a significant amount of conversion capability. Thyroid patients without a thyroid typically lose about 25% of their ability to make T3 (mostly through conversion) – this conversion capability cannot be replaced.

I no longer think adrenals need to heal. I believe that there can be hypothalamic-pituitary dysfunction – often after prolonged stress, and often because of daytime dosing of thyroid medication and sometimes due to poor conversion or other issues.

Fixing factors that influence conversion like iron, vitamins, and selenium can help, but will not fix it if there is a fundamental issue like thyroid tissue loss or one of the gene defects.

Sometimes it needs the raising of FT3. Sometimes this raising needs to happen in the night – hence my Circadian T3 Method (CT3M). CT3M can help to raise cortisol levels throughout the day and has done for many thyroid patients.

Sometimes, there is no obvious reason for the problem. However, I do believe it resides in the hypothalamic-pituitary area – not the adrenals.

Trying to support the adrenals using adrenal cortex in the hope that they will just get better is not something I believe will work at all. Nor will using other supplements aimed at ‘adrenal support’. The concept of supporting adrenals is not something I believe in any more.

If there is a massive reason like incredibly low iron, or low B12 or some other health issue which can be addressed whilst using adrenal cortex, it can be helpful. Fixing some fundamental health issue which is interfering with cortisol production is, of course, a very good thing to do, and might ultimately be sufficient to restore cortisol levels. But just taking the cortex is not a solution to make the adrenals become healthy again. Resting them is not a solution.

The two tests to rule out real adrenal organ issues are:

  1. The ACTH Stimulation or Synacthen test. This tests whether the adrenals can respond to ACTH stimulation. If they do well, the adrenals are not the issue – most thyroid patients pass this.
  2. The Insulin Tolerance Test. This tests if the pituitary is capable of responding to much lower blood sugar and produce enough ACTH. It does not prove that there is not any hypothalamic-pituitary dysfunction, but it does rule out proper hypopituitarism.

The above information is in ALL of my books.

The term Adrenal Fatigue is discussed all over the Internet. It is even present in some cortisol saliva test companies’ test results. In terms of cortisol saliva test results, I am one of the biggest fans of doing these. It is just the term that I think is misleading.

When people talk of stages of adrenal fatigue, it simply means stages of failure to produce cortisol and Dhea (both of which are stimulated by ACTH). It is not just nomenclature or giving things the right name. It is about understanding what is really causing the problems.

Nursing the adrenals back to health by supporting with adrenal glandulars or adrenal cortex, is not going to fix the fundamental issue with low cortisol.

I  realise that a lot of these comments may cause consternation, but I believe them to be true, based on the research I have done, the incredibly smart people that I have spoken with, and the experience I have had with working with many low cortisol patients.

I hope you found this helpful.

Best wishes,


(Updated in February 2019)

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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