Marker Cortisol

Marker Cortisol

July 26, 2021


What is cortisol?

Cortisol is often called the “stress hormone”. It is produced by our adrenal glands, which are located above the kidneys, in response to stressful situations that trigger the “fight or flight” response. Production of cortisol is regulated by the hypothalamus and pituitary gland in the brain.

When faced with acute stress, the spike in cortisol levels increases glucose production in the liver to supply our brain and muscle with energy and narrows the arteries to increase blood pressure and improve delivery of oxygenated blood to our muscles. At the same time, non-essential functions of the body, such as the immune system, are suppressed.

The levels of cortisol in blood varies throughout the day and plays an important role in the body’s normal sleep-wake cycle. For people with normal circadian cycles, cortisol peaks in the early morning hours to promote wakefulness and help you stay alert during the day. When cortisol levels drop during the evening, you will start to feel tired and drowsy. Unconventional sleep schedules, such as shift work, jet-lag, or sleep disorders can cause changes in secretion patterns of cortisol.

In short, it is useful to analyse cortisol levels in the blood to:

  • Assess adrenal function

  • Detect Addison’s disease

  • Detect Cushing syndrome

  • Investigate possible reasons behind conditions such as osteoporosis (low bone density), high blood pressure, central obesity and high blood pressure.

Why is this analysis important?

Cortisol is essential for life. People with damaged adrenal glands who are unable to produce enough cortisol will have a hard time maintaining normal blood pressure and blood sugar levels and risk death if the condition is left untreated. Luckily, this condition, called Addison’s disease, is rather rare.

It is far more common for people to have chronically elevated cortisol levels. This is often a consequence of our fast-paced modern lifestyle, and can lead to weight gain (especially around the abdomen), low bone density (osteoporosis), high blood pressure, high blood sugar, digestion problems, muscle weakness, sleep problems and dysregulated immune system. Very high levels of cortisol, caused by either long-term treatment with glucocorticoids-steroid hormones that are chemically similar to natural cortisol or by tumors in the pituitary gland or adrenal gland, can lead to a condition called Cushing syndrome.


The reference range for cortisol levels in the blood varies depending on the time of the day the test is taken. It can also be different depending on the laboratory and technique used. Doctors usually also take into account a number of factors when evaluating cortisol values.

High cortisol levels in the blood may be associated with:

  • High level of stress

  • Abnormal circadian cycles

  • Pharmacological treatment with certain corticosteroids

  • High alcohol consumption

  • Major depression

  • Poorly controlled diabetes

  • Obesity

  • Certain tumors

  • Oestrogen treatment such as contraceptive pills or hormone replacement therapy

Low cortisol levels in the blood may be associated with:

  • Adrenal insufficiency

  • Addison’s disease

  • Pharmacological treatment with certain corticosteroids

Other Considerations

Cortisol levels vary during the day. It is recommended to take the test in the morning for correct interpretation.

A number of drugs can affect the levels of cortisol including oral contraceptives (birth control pills), hormone replacement therapy (HRT) that contains oestrogen, oral corticosteroids (also called steroids, such as hydrocortisone, prednisolone, dexamethasone) and spironolactone. A cortisol test should not be taken when you are taking those drugs. Please discuss with your doctor what you should do with your medication if you wish to take the cortisol test.

Corticosteroids for local treatment, in the form of sprays, creams and gels do not interfere with the cortisol test.


Measurement of cortisol in serum and saliva. Lynnette K Nieman, MD. UpToDate Sep 29, 2019

Evaluation of Endocrine Function. Helena A. Guber y Amal F. Farag. Henry's Clinical Diagnosis and Management by Laboratory Methods, Chapter 24, 362-399