Quick Facts
- Sample: Saliva
- Fasting: Not required
- Turn-around: 5-7 business days once the lab receives the specimen. May take longer based on weather, holiday or lab delays.
Benefits
- Track your daily stress rhythm - Measures cortisol at four key times to reveal your body's natural stress patterns
- Detect adrenal dysfunction early - Identifies imbalances before symptoms worsen, supporting proactive health decisions
- Convenient at-home testing - No clinic visits or blood draws required; simple saliva collection
- Clinical-grade accuracy - Salivary testing shows >90% sensitivity for detecting subtle adrenal issues
- Personalized health insights - Results guide targeted stress management and lifestyle improvements
- Complete privacy - Confidential reporting
Who Is This Test For?
- Individuals experiencing chronic stress, fatigue, or unexplained energy crashes
- People with sleep disturbances or irregular sleep-wake cycles
- Those with suspected adrenal dysfunction (Addison's or Cushing's syndromes)
- Anyone seeking to understand their body's stress response patterns
- Health-conscious individuals pursuing preventive wellness screening
- People with mood changes, immune concerns, or stress-related symptoms
How It Works – Just 3 Steps
Order and receive your kit - Kit arrives with clear instructions and prepaid shipping materials
Collect four saliva samples - Simple collections upon waking, before lunch, before dinner, and before bed
Ship and receive results - Send samples overnight (Mon-Thu); get secure results in 5-7 business days
FAQ
How accurate is saliva testing for cortisol? Saliva accurately reflects "free" cortisol and is recommended by the Endocrine Society for diurnal rhythm assessment.
What preparation is needed before testing? Avoid eating, smoking, drinking (except water), or brushing teeth 30 minutes before each collection.
When should I collect the samples? On a typical, non-stressful day at four specific times: morning wake-up, before lunch, before dinner, and bedtime.
What do abnormal results indicate? Flattened curves or consistently high/low levels may signal adrenal dysfunction requiring physician evaluation.
Can medications affect my results? Yes, consult your provider about medications that may influence cortisol before testing.
How often should I repeat this test? Typically every 6-12 months for chronic cases, or as recommended by your healthcare provider.
More Details
What is the purpose of this test?
The Diurnal Cortisol (Cx4) test measures cortisol levels at four critical timepoints throughout a single day to evaluate your body's stress response and adrenal gland function (Mayo Clinic 2024). Cortisol, your primary stress hormone, follows a natural daily rhythm—highest in the morning to help you wake up, then gradually declining throughout the day.
This comprehensive assessment captures your complete cortisol curve, revealing patterns that single-point tests might miss. By understanding your cortisol rhythm, you and your healthcare provider can identify stress-related disorders, adrenal dysfunction, and develop targeted treatment strategies.
Who would benefit from this test?
This test is particularly valuable for individuals experiencing symptoms that may indicate cortisol imbalance or adrenal dysfunction (Cleveland Clinic 2023). Those with chronic stress, persistent fatigue, sleep disturbances, or unexplained mood changes often benefit from cortisol rhythm analysis.
People with suspected adrenal disorders, immune system concerns, or irregular energy patterns throughout the day should consider this assessment. Additionally, health-conscious individuals pursuing preventive wellness screening can use this test to establish baseline cortisol patterns and monitor stress management effectiveness over time.
When should I order the Diurnal Cortisol (Cx4) - ZRT Test Kit?
Order this test if you or your healthcare provider suspect abnormal stress hormone patterns or symptoms of adrenal imbalance. Consider testing when experiencing persistent fatigue, irregular sleep patterns, difficulty managing stress, or unexplained mood fluctuations.
This test is also valuable as part of preventive wellness screening, especially for high-stress lifestyles or family history of adrenal disorders. Schedule testing during a typical week, avoiding major stressors, illness, or significant schedule changes that might affect natural cortisol rhythms.
How do I interpret the results?
Your results display cortisol values at each timepoint compared to healthy, time-adjusted reference ranges (ZRT Laboratory 2024). The report includes interpretation tools and visual curves showing your daily cortisol pattern.
Normal curve (high AM, gradual decline)
- What it means: Healthy adrenal function
- Typical action: Maintain current lifestyle
Flattened curve (little variation)
- What it means: Adrenal fatigue or dysfunction
- Typical action: Consult healthcare provider
Consistently high levels
- What it means: Chronic stress or Cushing's syndrome
- Typical action: Medical evaluation needed
Consistently low levels
- What it means: Adrenal insufficiency or Addison's disease
- Typical action: Urgent medical consultation
Abnormal cortisol patterns affect an estimated 15 million U.S. adults with ongoing fatigue or stress-related symptoms.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No fasting is required for this saliva-based test. However, avoid eating, smoking, drinking anything except water, or brushing your teeth for 30 minutes before each saliva collection (ZRT Laboratory 2024).
Plan to test on a typical, non-stressful day when following your normal routine. Consult your healthcare provider about medications that might affect cortisol levels. Ensure you can collect samples at the required four timepoints without significant schedule disruptions.
How often should I get tested?
- Initial assessment: Baseline test, then 3–6 months
- Chronic stress management: Every 6–12 months
- Adrenal dysfunction monitoring: Every 3–6 months
- Treatment response tracking: Every 2–4 months
- Wellness maintenance: Annually or as symptoms change
Why early detection matters
Early detection of adrenal dysfunction can prevent complications and reduce long-term healthcare costs (Endocrine Society 2023). Delayed diagnosis is linked to increased morbidity and more complex treatment requirements.
With an estimated three in four U.S. adults experiencing prolonged stress that can disrupt cortisol patterns, proactive monitoring enables timely interventions (American Psychological Association 2023). Early identification allows for lifestyle modifications, stress management strategies, and medical treatments before symptoms become severe or irreversible.
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