Cortisol analysis: when to take it and what the stress hormone shows

Cortisol and stress: the invisible control mechanism

Imagine that the body is a complex system that reacts to external stimuli every second. These reactions are coordinated by many processes, and one of them is the secretion of cortisol. This hormone is produced in the adrenal glands and is a key element of the protective response to stress. Normally, it helps to adapt, but if it is produced too much or too little, this is reflected in the general well-being and health. An analysis of cortisol allows you to determine whether this system is working correctly and whether chronic fatigue or irritability is a consequence of hormonal imbalance.

What is cortisol?

Cortisol is a hormone that regulates the body's response to stress, controlling blood sugar levels, blood pressure, metabolism, and immune function. Its levels naturally fluctuate throughout the day, peaking in the morning and declining toward evening. These daily fluctuations must be taken into account when interpreting test results.

Indications for taking the analysis

A doctor usually orders a cortisol test if they suspect adrenal gland pathology or hormonal disorders. Symptoms that warrant a test include:

• constant fatigue without an objective reason
• sudden weight gain or loss
• pressure problems
• insomnia or circadian rhythm disturbances
• frequent colds, weakened immunity
• decreased libido
• infertility
• menstrual cycle disorders

What are the types of cortisol tests?

Cortisol can be measured in blood, urine, or saliva. Depending on the purpose of the test, your doctor may order one of three options:

Blood tests are usually performed twice: in the morning (between 7:00 and 9:00 AM) and in the evening (after 5:00 PM) to assess daily dynamics. Urine analysis gives an average value per day, and saliva allows you to estimate the active fraction without the stress of blood sampling.

Preparing for a cortisol test

To obtain reliable results, it is important to follow the recommendations:

• donate blood on an empty stomach in the morning (preferably between 7:00 and 10:00)
• do not smoke before the analysis
• refrain from physical exertion and stress during the day
• do not consume alcohol and caffeine for 24 hours
• inform the doctor about all medications, especially hormonal ones

To collect urine, you must follow the instructions: collect all urine for 24 hours in a special container, store it in a cool place, and do not miss a single bowel movement.

Normal indicators

The cortisol norm depends on the type of analysis and the time of collection:

• in the blood in the morning: 140–690 nmol/l
• in the blood in the evening: 50–330 nmol/l
• in daily urine: 55–248 nmol/day

The results are interpreted in the context of the patient's circadian rhythm and general condition.

What do deviations mean?

Elevated cortisol levels may indicate:

• chronic stress or physical overexertion
• Itsenko-Cushing's syndrome
• pituitary or adrenal gland neoplasm
• adiposity
• in women - pregnancy

A reduced level is characteristic of:

• Addison's disease
• hypothyroidism
• long-term glucocorticoid therapy
• anorexia
• severe exhaustion

What do doctors say?

«"If a patient complains of inexplicable fatigue, depression, or sudden weight fluctuations, I always recommend checking the cortisol level. This indicator often helps to identify hidden pathology," says endocrinologist Iryna Sushko.

«"Cortisol is a kind of indicator of how well the body copes with the load. A timely analysis allows you to detect violations even before serious symptoms appear," says therapist Andriy Gumenyuk.

Cortisol is key to understanding how your body copes with physical and psychological stress. If you're experiencing chronic fatigue or have symptoms that are hard to explain, a cortisol test can provide a clear picture of your hormonal balance and help you find the cause of your changes in well-being.