Cortisol is a steroid and a stress hormone. Production of cortisol is stimulated when stress is triggered — whether physical, mental or emotional. It plays an important role in the different metabolic processes in the body. Through its increased distribution in stress situations, it is able to provide energy by consuming sugar, fat and protein reserves. Through immune processes, cortisol also helps with its anti-inflammatory and anti-allergic effect, and has an important function in maintaining the health of the body.
What Happens When Cortisol Levels Are Too High?
Chronic stress is unhealthy — and stress is the most important impulse that causes the increase in cortisol distribution. If cortisol levels are too high, symptoms can include immunodeficiencies, depression, physical exhaustion, metabolic disorders, diabetes, obesity and sleeping disorders. Chronically elevated cortisol is one of the most common and most overlooked drivers of weight gain, belly fat and fatigue.
What Happens When Cortisol Levels Are Too Low?
Just the same, excessively low cortisol levels can interfere with wellbeing. Cortisol is vital — apart from the provision of energy reserves, it also plays a role in cardiovascular health, gastrointestinal health, the immune system and brain function. Chronically low cortisol levels should therefore be treated medically.
A low cortisol level can be an indicator for an infection in the adrenal cortex, a deficiency of the adrenal glands or adrenal fatigue, as cortisol is produced in that area. A dysfunction of the pituitary gland can also be the cause for a low cortisol level, as the hormone ACTH is distributed there, which gives the adrenal cortex the impulse to distribute cortisol.
It is advisable to have your cortisol levels tested, especially if you are quickly exhausted and suffer from fatigue, or if you are generally experiencing unexplained health problems. Our Adrenal Function Saliva Test Kit (LCMS) measures cortisol at four time points across the day alongside DHEA-S — providing a clear picture of your adrenal rhythm and HPA axis function using gold-standard LCMS analysis.
Cortisol and Burnout
Burnout describes the condition of prolonged emotional exhaustion as a reaction to chronic stress — people who are affected feel “burnt out.” In today’s performance-orientated society, burnout is no longer a rarity. Everyday work can, for some people, ensure continuous stress which, in the beginning, leads to an intensive phase of cortisol distribution. However, if this phase drags on, the chronic stress can lead to the exhaustion of the adrenal cortex, causing it to produce less cortisol — leading to a cortisol deficiency. At first, only the morning cortisol levels are reduced, but over time the cortisol levels fall below the standard levels.
The morning cortisol pattern is particularly revealing. Our Cortisol Awakening Response (CAR) Test (LCMS) measures the sharp rise in cortisol that occurs in the 30–45 minutes after waking — one of the most sensitive indicators of HPA axis health and a key early marker of burnout and adrenal exhaustion.
Why Regular Cortisol Testing Matters
Both too low and too high cortisol levels can cause unpleasant symptoms. To avoid these, it is recommended to regularly check your cortisol level. Our All Day Cortisol Test (4-Point LCMS) captures the full diurnal cortisol rhythm at four time points across the day — the most comprehensive way to assess whether your cortisol pattern is contributing to fatigue, weight gain, sleep problems or burnout.
If you are suffering from burnout or suspect adrenal dysfunction, it is important that you talk to your doctor. Testing provides the objective data needed to guide an effective, personalised treatment plan.
Originally ZRT Laboratory. Reproduced with permission. Last reviewed: May 2026.