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Cortisol Stress Hormone Test

Feb 3, 2026

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Cortisol Stress Hormone Test

A cortisol blood test measures your body's primary stress hormone, produced by the adrenal glands—with abnormal levels (either high or low) causing symptoms including chronic fatigue, weight gain (especially belly fat), anxiety, depression, sleep disturbance, and weakened immunity. Because cortisol follows a natural daily rhythm (highest in the morning, lowest at night), testing timing matters.

At Blood Test London, cortisol testing costs from £245 with results in 2-3 days.

Check Your Cortisol Levels

Understanding Cortisol: Your Stress Hormone

Cortisol is essential for life—it helps you:

  • Wake up in the morning

  • Respond to stress

  • Regulate blood sugar

  • Control inflammation

  • Maintain blood pressure

  • Support immune function

The Problem: Chronic Stress

Modern life often keeps cortisol elevated chronically, leading to:

  • Weight gain (especially abdominal)

  • Muscle breakdown

  • Weakened immunity

  • Poor sleep

  • Anxiety and depression

  • Brain fog

  • Accelerated aging

Normal Cortisol Levels

Morning Cortisol (8-9am) - Best Time to Test

Level (nmol/L)

Interpretation

170-500

Normal morning range

Below 170

Low—investigate adrenal insufficiency

Above 500

High—investigate Cushing's or chronic stress

Cortisol Daily Rhythm

Time

Expected Level

8am

Highest (peak)

12pm

Declining

4pm

Lower

Midnight

Lowest (trough)

Testing should be done at 8-9am for standard assessment.

Signs of Cortisol Imbalance

High Cortisol Symptoms

  • Weight gain, especially around the middle

  • Round "moon" face

  • Thin skin that bruises easily

  • Muscle weakness

  • High blood pressure

  • High blood sugar

  • Mood changes (anxiety, irritability)

  • Difficulty sleeping

  • Reduced libido

  • Irregular periods

Low Cortisol Symptoms

  • Extreme fatigue (not relieved by sleep)

  • Muscle weakness

  • Weight loss and poor appetite

  • Low blood pressure

  • Dizziness when standing

  • Salt cravings

  • Darkening of skin

  • Depression

  • Brain fog

Get Your Cortisol Checked

Conditions Affecting Cortisol

Causes of High Cortisol

  • Chronic stress (most common)

  • Cushing's syndrome (overproduction)

  • Pituitary tumours (ACTH-producing)

  • Adrenal tumours (cortisol-producing)

  • Steroid medications (prednisone, etc.)

  • Depression, alcoholism, obesity (can elevate cortisol)

Causes of Low Cortisol

  • Addison's disease (adrenal insufficiency)

  • Pituitary problems (secondary insufficiency)

  • Stopping steroid medication (suppressed adrenals)

  • Adrenal fatigue (controversial but some believe chronic stress depletes adrenals)

How to Optimise Cortisol Naturally

For High Cortisol

Strategy

How It Helps

Sleep 7-9 hours

Allows cortisol to normalise overnight

Meditation/mindfulness

Proven to lower cortisol

Exercise (moderate)

Reduces stress, but avoid overtraining

Limit caffeine

Especially after 12pm

Reduce alcohol

Disrupts cortisol rhythm

Adaptogens

Ashwagandha has evidence for lowering cortisol

Social connection

Reduces stress hormones

Nature exposure

20 minutes in nature lowers cortisol

For Low Cortisol

  • Address underlying cause (medical evaluation essential)

  • Gentle exercise (not intense)

  • Adequate salt intake

  • Regular meal times

  • Stress management

  • Possible medication (hydrocortisone replacement if Addison's)

Our Cortisol Testing Options

Morning Cortisol - £265

  • Single morning cortisol

  • Doctor review

Cortisol + DHEA - £295

  • Cortisol and DHEA-S (adrenal function pair)

  • Cortisol:DHEA ratio

Full Adrenal Profile - £345

  • Morning cortisol

  • DHEA-S

  • ACTH (pituitary driver)

  • Doctor review and consultation

Stress & Energy Panel - £395

  • Adrenal hormones

  • Thyroid function

  • Key vitamins (D, B12, iron)

Book Your Cortisol Test

Book Your Cortisol Test

Price: From £245
Results: 2-3 days
Doctor review: A doctor always reviews every result
Requirements: Test at 8-9am, before eating or exercising

Book via WhatsApp

Phone: 020 3951 3429

FAQ

What time should I test cortisol?
8-9am for morning cortisol (the standard test). Avoid eating, exercising, or caffeine before the test.

Is "adrenal fatigue" real?
It's controversial. While not a recognized medical diagnosis, chronic stress does affect adrenal function. We test the measurable hormones.

Can stress really affect my health this much?
Yes—chronic cortisol elevation is linked to obesity, diabetes, heart disease, immune dysfunction, and mental health problems.

How long does it take to normalise cortisol?
With lifestyle changes, improvements can be seen in weeks to months. It depends on severity and underlying causes.

Should I test cortisol if I'm stressed?
If stress is causing symptoms, testing helps determine if cortisol is actually elevated and guides treatment.

Blood Test London by The Wellness. Cortisol stress testing from £245, results in 2-3 days.