Why is My Cortisol Low?


Cortisol plays an important role in our health and well-being each second of every day, yet few individuals understand exactly what it does. Even fewer understand why cortisol levels drop, making a low test result all the more confusing.

A brief outline on the hormone may help. Cortisol is a steroid hormone, specifically a glucocorticoid, that the body needs to cope with the effects of stress. It also helps to boost blood sugar levels between meals, regulate blood pressure, control inflammation and set the sleep/wake cycles. It affects mood, helps to set the metabolic rate and can also impact on the behaviour of other organ systems (such as the thyroid, liver, immune system and digestive tract). Cortisol is a big deal.

Cortisol is produced when the brain, via signals originating in the hypothalamus and acted upon by the pituitary gland, send a signal down to the adrenal cortex. This signal, in the form of adreno-corticotrophic hormone (or ACTH), triggers enzyme activity at the gland. Specifically, these enzymes start converting steroid hormones, such as pregnenalone and progesterone, down a specific pathway until they end up as cortisol.

The more stress the brain perceives, regardless of the source, the more it stimulates the adrenal glands. As a result, the harder these enzymes work and the more cortisol is produced. For this reason, practitioners can easily conclude that an individual with high cortisol levels has experienced excessive stress for a sustained period of time. This stress can come in the form of psychological worry, poor sleeping patterns, low blood sugar levels, too much coffee, excessive exercise or chronic infections, but it all counts.

So does this mean a person with low cortisol levels is relaxed and care-free? Not a chance. In every test result I have ever interpreted, the cause of low cortisol levels came down to two potential causes:

1. “Burnout” (the Adrenal Fatigue model) aka Primary Hypoadrenalism
This is often quoted as ‘the cause’ of low cortisol. To be fair, it does represent the most likely cause of low cortisol levels. In this model, the adrenal glands are over-stimulated for months or years at a time, with the enzymes working on over-drive to pump out a high level of cortisol. Then, the straw breaks the camel’s back. One stressor to many leads to enzyme dysfunction and reduced adrenal performance. The adrenals are no longer capable of producing sufficient cortisol, despite the stress levels placed upon them. A multitude of symptoms appear.

2. HPA Dysfunction aka Secondary Hypoadrenalism
The symptoms of this model are identical, yet the cause can be somewhat different.
In this model, the adrenal performance actually remains solid, the gland simply misses the stimulation from the hypothalamus and the pituitary. Reduced stimulation (reduced ACTH) means reduced cortisol production.

So, having got back a result on a test, how can you tell the cause of low cortisol levels? Many times, a simple Adrenal Stress Index test (a salivary test, performed four times over the course of a day) will reveal all you need to know. If the cortisol levels are high at one part of the day, or the DHEA levels remain normal or high, then we can know for sure that the brain has sent sufficient ACTH down to the adrenal glands. This fingers the blame purely on the adrenals. Sometimes I cannot make definite judgements from the ASI results alone, in which case a Synacthen test will demonstrate conclusively whether the low function of the adrenals is primary or secondary.

That being said, the clinical treatment for primary or secondary adrenal imbalance remains strikingly similar. In both forms, the patient must address all sources of stress in their life and remove as much as possible (in the short term, at least). Both forms will require temporary support to boost adrenal hormones into the normal range for, if this is not done, the other organ systems will continue to struggle; this means a continuation of symptoms and a continuation of stressload at the adrenals, the one thing we aim to avoid. Whenever HPA dysfunction is indicated, a plan to clear out chronic infections stands out as a priority, yet so many individuals with primary dysfunction of the adrenals also have unrecognised infectious issues that need to be addressed.

In all cases, there will be a definite cause (or causes) for low cortisol. These underlying issues must be addressed and appropriate adrenal support must be provided, but we must also acknowledge the the impact that adrenal imbalance has on the thyroid, immune system, digestive tract and liver and take steps to neutralise these potential stumbling blocks. Adrenal imbalance is a multi-faceted problem which requires multi-faceted treatment. When this concept is followed, progress is reliable and rapid and this confusing picture suddenly becomes less complex.