Cortisol is a hormone produced by the adrenal glands. Every cell in the body has receptors for both thyroid and cortisol.
When a person is hypothyroid, the adrenal glands are required to work harder than they otherwise would to help maintain metabolism. Overworked adrenal glands become less and less able to produce the amount of cortisol needed. Because thyroid hormones need cortisol to work in cells, a decrease in cortisol production reduces the utilization of the thyroid hormone that is produced, which in turn places more demands on the adrenals to produce cortisol. This creates a downward spiral suffered by many, without realizing the causes of their poor health.
There are certainly other reasons why the adrenal glands may decrease cortisol production over time, such as the stressful lifestyles that began to be so common in the second half of the 20th century. But it does not really matter which is the chicken and which is the egg – the end result is the same. The body systems that are dependent on cortisol and thyroid, and are the foundation of all good health, become compromised.
Is this an oversimplification? Sure. But understanding the intricate chemical cascades that take place in these body systems will not change how someone feels or what needs to be done.
We know from the experience of thousands of patients that adrenal fatigue does exist. Endocrinologists appear to be trained to recognize only the extremes of adrenal dysfunction -- either complete failure to produce hormones or runaway overproduction. This defies logic. Every other organ in the body has stages of dysregulation, disease or deterioration before it fails. Why would the adrenal glands be any different.
In his book Safe Uses of Cortisol, first published in 1981, William Jeffries, M.D., describes the concept of mild adrenal insufficiency and its connection to thyroid function.
Adrenal fatigue is the common term for low cortisol production that does not meet the medical definition of Adrenal Insufficiency or Addison’s Disease. However, in most cases the problem may not be that the adrenal glands are unable to produce cortisol. They are just as likely not getting the message from the pituitary to do so. This would make HPA (hypothalamic/pituitary/adrenal) Axis Dysfunction a more accurate description of the condition.
How to address this dysfunction depends on the degree to which it exists. This requires specific testing.