Cortisol (S-Korsol) is a hormone secreted in the adrenal cortex, a glucocorticoid. Cortisol affects the metabolism of carbohydrates. A small proportion of cortisol (approximately 5%) circulates freely in the bloodstream, and approximately three-quarters of it is bound to a protein in the blood. The production of cortisol is regulated by the pituitary gland.
The amount of cortisol varies over time. The highest amounts of cortisol in the blood are found in the morning, from 6:00 to 8:00, and the lowest in the evening from 20:00 to 22:00. Sleeping rhythm does not affect the circadian rhythm of cortisol. Cortisol concentration has to decrease during the night, because otherwise the body cannot relax and recharge.
The most important purpose of cortisol is to maintain adequate blood sugar content during efforts that require energy or stress. The cortisol level increases during both mental and physical stress, and it increases the production of sugar in the liver, gut, and kidneys. The sugar is released into the bloodstream so that the body has energy available for situations that require a fight-or-flight response.
The normal level of cortisol is useful for us, because it keeps us energetic, able to function, and motivated. Acute stress causes a sudden peak in the amount of cortisol in the blood. Prolonged high cortisol levels cause unpleasant symptoms and adrenal fatigue.
The body also needs cortisol for many important functions, such as metabolism, mental and physical stress reactions, control of inflammation and use of proteins, carbohydrates and fats, levelling of blood pressure, production of glucose from sources other than carbohydrates, and secreting hydrochloric acid and pepsin in the stomach.
When should cortisol be measured?
Cortisol can be measured in connection with the following symptoms:
- Trouble falling asleep
- Weight gain
- Muscle weakness
- Muscle sensitivity and slow healing of wounds
- Anxiety and feelings of irritability
- High blood pressure
- Susceptibility to infection
- Memory problems
- Weak libido (loss of sex drive)
- Loss of appetite
- Irregular menstrual periods
- Menopause symptoms and intensified PMS symptoms
What does a cortisol test measure?
The test measures the amount of cortisol in the blood. It is important to take account of the normal circadian fluctuation in cortisol in the measurement. Stress can elevate the test results. Together with measurement of the pituitary gland hormone ACTH, it is possible to diagnose a hyperactive or hypoactive adrenal cortex.
How to interpret the S-Korsol test result?
Reference values of cortisol:
- Morning sample, age ≥ 19 y: 130–550 nmol/l
- Morning sample, age 17-18 y: 97-506 nmol/l
- Afternoon levels are approximately 25–40% lower than morning levels.
The reference values of this examination have changed 6.10.2022. You will find your own result's reference values from My LOUNA in touch with the graph. Read more about defining reference values.
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
What can cause elevated levels in the S-Korsol?
When cortisol is elevated, it prevents the function of insulin in cells and increases the level of blood sugar, which results in weight gain. Continuously elevated cortisol increases the risk of diabetes and interferes with the immune system.
Elevated cortisol levels can be caused by:
- A cortisol-secreting tumour
- Excessive hormonal simulation of the adrenal cortex by the pituitary gland
- Excess weight
- Anorexia nervosa
- Oestrogen therapy
- A sudden infectious disease
- Cushing's syndrome
What can cause decreased levels in the S-Korsol?
Low cortisol levels can be caused by:
- A hypoactive adrenal cortex or pituitary gland (Addison’s disease)
- Excessive male hormone production by the adrenal cortex
- Hyperthyroidism (overactive thyroid)
- Protein deficiencies (nephrotic syndrome, severe liver damage)
The most typical additional S-Korsol tests:
- Blood sugar gives the body energy (1468 fP-Gluk)
- Haemoglobin A1c measures long-term blood sugar (6128 B-HbA1C)
- Insulin (6040 fS-Insu)
SYNLAB test list: Cortisol https://www.yml.fi/tuotekuvaus_show.php?tuotenro=233
Terveyskirjasto health library: Kortisoli https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=ltt01749&p_hakusana=kortisoli
Suomen endokrinologiyhdistys: Cushingin oireyhtymä https://www.endo.fi/tietoa-endokrinologisista-sairau/potilasohjeet/cushingin-oireyhtyma/
Aivolisäkepotilasyhdistys Sella: Kortisolitasapaino https://sellanet.com/lisamunuainen/kortisolitasapaino/
Fasting is not required
This examination does not require fasting