Cortisol

Cortisol is a hormone secreted by the adrenal cortex, commonly referred to as the “stress hormone” due to its role in the body’s stress response. It accounts for over 80% of the total concentration of 17-hydroxycorticosteroids in the blood. Most cortisol in the blood is bound to transcortin (corticosteroid-binding globulin, CBG) and albumin (around 90%). This binding mechanism prevents its inhibition during filtration in the kidneys or liver during the conjugation process. The concentration measured in blood tests represents free cortisol. Determining cortisol levels is important for assessing the condition and function of the adrenal glands, pituitary gland, and hypothalamus.

The synthesis and release of cortisol are regulated by adrenocorticotropic hormone (ACTH) via a negative feedback mechanism. As free, unbound cortisol levels in the blood increase, ACTH secretion decreases. Conversely, when cortisol levels are low, ACTH concentration rises, stimulating the adrenal cortex until cortisol reaches normal levels.

It’s important to note that cortisol levels fluctuate throughout the day, with both cortisol and ACTH following a diurnal pattern. Cortisol and ACTH levels begin rising in the early morning, peaking between 6 and 8 a.m., then declining to their lowest levels in the early evening and around midnight. Common practice is to measure morning cortisol (at 8 a.m.) and afternoon/evening cortisol (4–6 p.m.) levels to establish a “cortisol status.” Sleep-wake rhythm disruptions can affect this secretion cycle.

Elevated Cortisol Levels May Occur in:

• Cushing’s syndrome
• Excessive ACTH secretion
• Chronic stress
• Alcoholism
• Endogenous depression
• Chronic systemic diseases
• Estrogen therapy
• Pregnancy
• Obesity

Decreased Cortisol Levels May Occur in:

• Primary and secondary adrenal insufficiency

Cortisol has multiple essential functions in the body. It is crucial for managing the circadian rhythm (sleep-wake cycle), influencing sugar metabolism, and playing a role in immune responses and inflammation processes. Therefore, maintaining its concentration within the normal range is essential.

Today, the impact of a fast-paced lifestyle and chronic stress is increasingly recognized. Prolonged exposure to stressful situations increases the secretion of stress hormones, including cortisol. Constantly elevated hormone levels as a stress response lead to various metabolic changes, posing risks for several conditions:

• High blood pressure and other cardiovascular issues
• Obesity
• Depression
• Sleep disturbances
• Anxiety
• Digestive problems
• Muscle pain and tension
• Headaches
• Concentration difficulties

No special patient preparation is required for this test. It is recommended to perform the blood test during the follicular phase of the cycle (from the second to fourth day) in the morning after resting for 20 minutes to ensure the sample is taken in a relaxed state.