Cortisol is a steroid hormone produced by the adrenal glands, which are located at the top of each kidney. Often referred to as the “stress hormone,” it belongs to the glucocorticoid class and is known as hydrocortisone in a medical context.

Roles of Cortisol

• Stress response : Increases blood sugar levels and improves brain function.
• Metabolism : Regulates the use of carbohydrates, fats and proteins.
• Inflammation Control : Suppresses inflammation and regulates the immune response.
• Arterial pressure : Manages water and electrolyte balance to maintain stable blood pressure.
• Mood Regulation : Influences mood, motivation, and fear response.

The Daily Cortisol Rhythm

Cortisol follows a Circadian rhythm, fluctuating naturally during the day:

• Morning Peak : Levels are highest between 6 am and 8 am to help wake up.
• Nocturnal drop : Levels gradually decrease to allow for relaxation and sleep.

Disturbances in this rhythm, caused by stress or sleep disorders, can affect overall health.

Cortisol can be measured by blood, urine, or saliva tests. Each method offers advantages and disadvantages.

Blood tests

• Benefits : Accurate and reliable, ideal for diagnosing conditions like Cushing's syndrome or Addison's disease.
• Disadvantages : Invasive and do not capture the variations of the day.

Urine tests

• Method : Collection of urine over 24 hours to measure the cortisol excreted over a full day.
• Benefits : Provides an overview of fluctuations.
• Disadvantages : Inconvenient, requiring accurate collection.

Saliva tests

• Method : Saliva samples taken at various times of the day.
• Benefits : Non-invasive and suitable for frequent follow-up.
• Disadvantages : Less accurate than blood tests.

Cortisol levels peak early in the morning, between 6 am and 8 am, helping the body wake up and prepare for daily activities. As the day progresses, cortisol levels gradually decrease to reach their lowest point in the evening and during the night. This rhythm is essential for maintaining energy balance, concentration, and a healthy stress response.

Blood Cortisol

• Morning : 10—20 mcg/dL.
• Afternoon : 3—10 mcg/dL.

Urinary cortisol

• 24 hour collection : 10—55 mcg/24 h.

Salivary Cortisol

• Morning : 10.2—27.3 ng/ml.
• Soir : 2.2—4.1 ng/mL.

High Cortisol Levels (Hypercortisolism)

Causes

• Cushing's syndrome : Overproduction of cortisol due to tumors.
• Chronic stress : Driven to consistently high levels.
• Medications : Some glucocorticoids increase cortisol.

Symptoms

• Weight gain (especially in the abdomen and face).
• High blood pressure.
• Mood changes (anxiety, irritability).
• Fragility of the skin (easy bruises, stretch marks).

Implications

• Cardiovascular diseases : Increased risk of strokes and heart attacks.
• Diabetes : Increased blood sugar levels.
• osteoporosis : Fragile bones.

Causes

• Addison's disease : Autoimmune destruction of the adrenal glands.
• Pituitary disorders : Affect TSH production.
• Abrupt withdrawal of corticosteroids : Reduces the natural production of cortisol.

Symptoms

• Persistent fatigue.
• Unintentional weight loss.
• Muscle weakness.
• Low blood pressure (dizziness, fainting).

Implications

• Adrenal crisis : Medical emergency characterized by pain, vomiting, and confusion.
• Electrolyte imbalance : Affects heart and nerve functions.

Factors Influencing Cortisol

• Age : Production may decrease with age.
• Stress : Chronic stress increases cortisol.
• Sleep : Poor sleep disrupts the circadian rhythm.
• Medications : Some treatments (glucocorticoids, oral contraceptives) change levels.

Reducing High Levels

1. Relaxation techniques : Meditation, yoga and deep breathing.
2. Moderate physical activity : Reduces stress without overloading the body.
3. Diet : Limit caffeine and choose foods rich in fiber and omega-3.
4. Stress Management : Develop coping mechanisms (journaling, leisure).

Increase in low levels

1. Corticosteroids : Prescribed in case of severe hypocortisolism.
2. Healthy Diet : Foods rich in vitamin C, zinc, and magnesium to support the adrenal glands.
3. Sleep : Establish a regular sleep routine.

Preventive Tips for Balanced Cortisol

• Regular exercise : Promote moderate activities such as walking or swimming.
• Restful sleep : Maintain consistent bedtime schedules.
• Balanced diet : Choose whole grains, fruits, vegetables, and healthy fats.
• Hydration : Drink enough water throughout the day.
• Social life : Maintain positive relationships to reduce stress.

Proactively managing cortisol levels contributes to better overall health, preventing complications related to stress and hormonal imbalances.

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