Cortisol

What is Cortisol?

Cortisol is a steroid hormone produced by the adrenal glands. Often called the "stress hormone," it helps regulate metabolism, blood pressure, immune function, and the body's response to stress.

Why is it Important?

Cortisol is essential for:

• Regulating blood sugar and metabolism
• Reducing inflammation
• Controlling blood pressure
• Supporting immune system function
• Managing stress response
• Regulating sleep-wake cycle

Normal Ranges (Time-Dependent)

Cortisol follows a diurnal rhythm — highest in the morning, lowest at night.

Time of Day	Range	Unit
Morning (6-8 AM)	6 – 23	µg/dL
Afternoon (4 PM)	3 – 16	µg/dL
Evening (midnight)	< 7.5	µg/dL

What Do Abnormal Results Mean?

High Cortisol (Hypercortisolism)

Common causes include:

• Cushing's syndrome (chronic cortisol excess)
• Cushing's disease (pituitary tumor)
• Adrenal tumors
• Ectopic ACTH production (lung cancer)
• Chronic stress or depression
• Alcohol abuse
• Medications (corticosteroids like prednisone)

Symptoms: Weight gain (especially around abdomen), moon face, high blood pressure, purple stretch marks, easy bruising, muscle weakness.

Low Cortisol (Hypocortisolism)

Common causes include:

• Addison's disease (adrenal insufficiency)
• Hypopituitarism (pituitary gland failure)
• Sudden steroid withdrawal
• Sheehan syndrome (postpartum pituitary necrosis)
• Congenital adrenal hyperplasia

Symptoms: Fatigue, weight loss, low blood pressure, hyperpigmentation (darkening of skin), salt craving, dizziness.

Types of Cortisol Tests

• Serum cortisol: Blood test, time-specific (AM vs PM)
• 24-hour urinary cortisol: Measures total daily production
• Late-night salivary cortisol: Screens for Cushing's syndrome
• ACTH stimulation test: Tests adrenal function

When Should You Get Tested?

Cortisol testing may be ordered if you have:

• Symptoms of Cushing's syndrome or Addison's disease
• Unexplained weight gain or loss
• Persistent fatigue or muscle weakness
• High blood pressure resistant to treatment
• Abnormal ACTH levels
• Monitoring steroid therapy withdrawal