Cortisol

🔹 What is Cortisol?

Cortisol is a steroid hormone belonging to the glucocorticoid class. It is produced and secreted by the adrenal cortex (specifically the zona fasciculata of the adrenal glands) in response to stress and low blood-glucose concentration. It plays essential roles in metabolism, immune response, stress adaptation, and maintaining homeostasis.

Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone.

Cortisol is produced in many animals, mainly by the zona fasciculata of the adrenal cortex in an adrenal gland. In other tissues, it is produced in lower quantities. By a diurnal cycle, cortisol is released and increases in response to stress and a low blood-glucose concentration.

It functions to increase blood sugar through gluconeogenesis, suppress the immune system, and aid in the metabolism of calories. It also decreases bone formation. These stated functions are carried out by cortisol binding to glucocorticoid or mineralocorticoid receptors inside a cell, which then bind to DNA to affect gene expression.

Cortisol is a hormone your adrenal glands make and release. It’s a glucocorticoid, a type of steroid hormone.

You may mainly think of cortisol when it comes to stress. But it’s an essential hormone that affects almost every organ and tissue in your body. It plays many other important roles, including:

• Regulating how your body uses glucose (sugar) for energy
• Decreasing inflammation
• Regulating blood pressure
• Helping control your sleep-wake cycle

Your body continuously monitors your cortisol levels to maintain steady levels (homeostasis). High or low cortisol levels can be harmful to your health.

🔹 Chemical and Biological Characteristics:

🔹 How is Cortisol Produced? (HPA Axis)

Cortisol is regulated by the hypothalamic-pituitary-adrenal (HPA) axis:

1. Hypothalamus releases CRH (corticotropin-releasing hormone)
2. CRH stimulates the anterior pituitary to release ACTH
3. ACTH acts on the adrenal cortex to produce cortisol
4. Negative feedback: High cortisol inhibits CRH and ACTH production to prevent excess

🔹 Functions of Cortisol:

1. 🧠 Stress Response

cortisol plays a key role in managing your body’s stress response. Your body releases cortisol when you experience any of the following types of stress, Acute (short-term) stress, Chronic (long-term) stress, and Traumatic stress

• Known as the “stress hormone”
• Increases alertness and energy during physical or psychological stress
• Ensures glucose availability for the brain and muscles

2. 🍞 Metabolic Regulation

Metabolism refers to the chemical processes in your body that allow you to live and function. Thousands of metabolic processes happen at all times.

Cortisol affects your metabolism by helping regulate how your body uses glucose (sugar) for energy. The hormone does this in many ways. For example, cortisol triggers your pancreas to decrease insulin and increase glucagon. Insulin lowers blood glucose (sugar). Glucagon raises it.

• Increases blood glucose by promoting:
  • Gluconeogenesis in the liver
  • Protein catabolism in muscle (amino acids converted to glucose)
  • Lipolysis (fat breakdown)
• Antagonizes insulin, reducing glucose uptake by cells

3. 🛡️ Anti-inflammatory and Immunosuppressive Effects

In short spurts, cortisol can boost your immunity by limiting inflammation. But if you have consistently high levels of cortisol, your body can get used to it. This can lead to inflammation and a weakened immune system.

• Suppresses inflammatory cytokines
• Inhibits immune cell activity (T-cells, macrophages)
• Used pharmacologically to treat inflammation, autoimmune diseases, and allergies

4. 💓 Cardiovascular Support

• Maintains vascular tone
• Enhances the effect of catecholamines (like epinephrine)
• Helps regulate blood pressure

5. 🧬 Other Roles

The exact way in which cortisol regulates blood pressure in humans is unclear. But elevated levels of cortisol can cause high blood pressure. And lower-than-normal levels of cortisol can cause low blood pressure.

Most people have lower cortisol levels in the evening when they go to sleep. And they have peak levels in the morning right before they wake up. This suggests that cortisol plays a key role in your circadian rhythm and how your body wakes up.

• Influences mood, behavior, and cognition
• Affects bone turnover and calcium metabolism
• Impacts reproductive system (can suppress sex hormones in chronic stress)

🔹 Cortisol and Circadian Rhythm:

• Cortisol secretion follows a diurnal rhythm:
  • Highest in the early morning (6–8 AM)
  • Lowest at midnight
• This rhythm is vital for sleep-wake cycles, metabolism, and immune function

🔹 Normal Cortisol Levels (Serum):

🔹How does my body control cortisol levels?

Your body has an elaborate system to regulate your cortisol levels. Your hypothalamus and pituitary gland control the cortisol production in your adrenal glands. The process goes like this:

1. When the cortisol level in your blood falls, your hypothalamus releases corticotropin-releasing hormone (CRH).
2. This directs your pituitary gland to make adrenocorticotropic hormone (ACTH).
3. ACTH then triggers your adrenal glands to make and release cortisol.

To have healthy cortisol levels, your hypothalamus, pituitary gland and adrenal glands must all be functioning properly.

🔹Clinical Relevance and Disorders:

🔼 High Cortisol Levels (Hypercortisolism)

If you have high levels of cortisol (hypercortisolism) for a long time, it’s usually Cushing syndrome. Causes of high cortisol levels and Cushing syndrome include:

• Taking high doses of corticosteroid medications, like prednisone, prednisolone or dexamethasone
• Tumors that produce ACTH — usually in your pituitary gland
• Adrenal gland tumors that cause excess cortisol

Causes:

• Cushing’s Syndrome
  • Pituitary adenoma (Cushing’s disease)
  • Adrenal tumors
  • Ectopic ACTH secretion
  • Exogenous glucocorticoids (medication)

Symptoms:

• “Moon face”, “buffalo hump”
• Central obesity with thin limbs
• High blood pressure
• Hyperglycemia/diabetes
• Mood swings, insomnia
• Skin thinning, bruising
• Weight gain, especially in your face and belly
• Fatty deposits between your shoulder blades
• Wide, purple stretch marks on your belly
• Muscle weakness in your upper arms and thighs
• High blood sugar, which often turns into Type 2 diabetes
• Excessive hair growth (hirsutism) in females
• Weak bones (osteoporosis) and bone breaks (fractures)

🔽 Low Cortisol Levels (Hypocortisolism)

Healthcare providers call lower-than-normal cortisol levels (hypocortisolism) adrenal insufficiency. There are two types of adrenal insufficiency: primary and secondary.

Primary adrenal insufficiency most often happens when your immune system attacks your adrenal glands. It’s called Addison’s disease. An infection or blood loss to the tissue in your adrenal glands can also lead to a lack of cortisol.

Secondary adrenal insufficiency happens if you have an underactive pituitary gland (hypopituitarism) or a pituitary tumor. These conditions can limit ACTH production, which limits cortisol production. You can also develop low cortisol levels after suddenly stopping treatment with corticosteroids.

Causes:

• Addison’s Disease (adrenal insufficiency)
• Secondary adrenal insufficiency (from pituitary failure or steroid withdrawal)

Symptoms:

• Fatigue and weakness
• Low blood pressure
• Low blood sugar (hypoglycemia)
• Weight loss
• Skin hyperpigmentation (Addison’s)
• Salt craving (due to aldosterone deficiency)

How can I reduce my cortisol levels?

If you have Cushing syndrome, you’ll need medical treatment to lower your cortisol levels. Treatment usually involves medication and/or surgery.In general, though, there are several ways to help lower your cortisol levels, including:

• Get quality sleep. Chronic sleep issues, like insomnia or working a night shift, can cause higher cortisol levels.
• Move your body. Regular physical activity helps improve sleep quality and reduce stress.
• Practice deep breathing exercises. Controlled breathing helps stimulate your parasympathetic nervous system, your “rest and digest” system. This helps lower cortisol levels.
• Enjoy yourself and laugh. Laughing promotes the release of endorphins and suppresses cortisol. Participating in fun activities can also promote feelings of well-being.
• Maintain healthy relationships. Having tense and unhealthy relationships can cause frequent stress.

🔹 Cortisol in Medicine:

Pharmacological Cortisol = Hydrocortisone

• Used as a medication in:
  • Adrenal insufficiency (replacement therapy)
  • Allergic reactions
  • Asthma and COPD
  • Autoimmune diseases (e.g. lupus, rheumatoid arthritis)
  • Shock or severe inflammation

🔹 Cortisol and Mental Health:

• Chronic stress → persistent high cortisol → linked to:
  • Anxiety and depression
  • Cognitive impairment
  • Sleep disturbances
  • Weakened immune system
  • Weight gain (especially abdominal fat)

🔹 Cortisol Testing:

• Blood tests (serum cortisol, ACTH stimulation test)
• Saliva test (midnight cortisol level, for Cushing’s diagnosis)
• 24-hour urine free cortisol
• Dexamethasone suppression test

🔹 Summary Table: