Quick Facts
- Sample: Four saliva collections (morning, midday, evening, bedtime) plus fingerstick blood spot
- Fasting: Not required; continue all medications and supplements
- Turn-around: Results within 5-7 business days from specimen receipt. May take longer based on weather, holiday, or lab delays.
Benefits
- Detect HPA axis dysregulation before clinical symptoms develop
- Eliminate needle anxiety and stress-induced cortisol elevation at home
- No physician gatekeeping; order directly and confidentially
- Track stress management and supplement effectiveness with objective data
- Reference ranges adjusted for age, sex, menstrual status, and supplementation.
Who Is This Test For?
- Individuals experiencing persistent fatigue, anxiety, mood changes, or poor sleep
- Those in high-stress professions (healthcare, law, finance, education) seeking baseline assessment
- Anyone monitoring interventions (meditation, exercise, supplements) with objective data
- People with trauma history or PTSD symptoms concerned about stress resilience
- Athletes and high-performers tracking stress capacity and recovery
How It Works - Just 3 Steps
- Order and Receive Kit: Order online, receive prepaid collection kit at home with clear instructions for saliva and blood spot sampling.
- Collect Samples: Collect four saliva samples at precise times (upon waking, 30 minutes post-waking, midday, evening) and one fingerstick blood spot; allow to dry completely and return via prepaid mail.
- Receive Results: Results arrive within 5-7 business days with graphical cortisol curve and biomarker analysis. For insight discuss with your healthcare provider.
FAQ
What does this test measure? The SB-644 charts your 24-hour cortisol rhythm (diurnal curve) via saliva and measures cortisol plus hormones affecting stress response (DHEA-S, SHBG, thyroid markers). This reveals whether your HPA axis, your body's stress system, is functioning optimally or dysregulated.
Who should consider this test? Anyone experiencing chronic stress symptoms (fatigue, anxiety, sleep problems, difficulty concentrating), those with depression or PTSD history, people in high-stress careers, and athletes monitoring stress resilience. Also useful when starting stress-management or supplement protocols.
How accurate is saliva testing compared to blood? Salivary cortisol has sensitivity and specificity exceeding 90% in peer-reviewed studies, comparable to serum cortisol (Endocrine Society 2024). Advantage: non-invasive repeated sampling avoids stress-induced cortisol elevation from needles, providing superior real-world accuracy.
Do I need to stop my medications or supplements before testing? No. Unlike many labs, ZRT adjusts reference ranges for common medications, hormones, and supplements. Continue your regular regimen to get results reflecting your actual physiological state.
What if my results are abnormal? Abnormal patterns may indicate chronic stress, burnout, depression risk, or sleep disruption. Discuss findings with your primary care provider or functional medicine practitioner; severe elevation warrants endocrinology referral.
Can I retest to track progress? Yes. Repeat testing at 8-12 week intervals objectively verifies whether lifestyle changes (exercise, meditation, sleep), diet modifications, or supplementation successfully normalize cortisol patterns. ZRT preserves historical results for comparison.
More Details
What is the purpose of this test?
The SB-644 measures cortisol at four time points throughout the day to chart your diurnal cortisol curve, revealing whether your HPA axis (stress system) functions optimally. Abnormal patterns indicate dysregulation linked to burnout, depression, anxiety, sleep disturbance, and reduced immune resilience. Optional Cortisol Awakening Response (CAR) enhancement captures the critical morning cortisol surge, a biomarker for stress capacity and mood stability.
What biomarkers are measured in this test?
Saliva Samples:
- Cortisol (4-point diurnal) - HPA axis function across 24-hour cycle; identifies dysregulation patterns
Blood Spot (Fingerstick):
- Cortisol - Point-in-time total cortisol measurement
- DHEA-S (Dehydroepiandrosterone-sulfate) - Anti-glucocorticoid hormone; low levels indicate chronic stress
- SHBG (Sex Hormone-Binding Globulin) - Elevated with high cortisol; indicates HPA-reproductive axis interaction
- TSH (Thyroid Stimulating Hormone) - Cortisol dysregulation impairs thyroid function
- fT3 (Free Triiodothyronine) - Active thyroid hormone; cortisol suppresses conversion
- fT4 (Free Thyroxine) - Free thyroid hormone; elevated cortisol lowers fT4 levels
- TPOab (Thyroid Peroxidase Antibodies) - Screens for autoimmune thyroiditis, comorbid with HPA dysregulation
Optional Enhancement:
- Cortisol Awakening Response (CAR) - Six-point collection capturing cortisol surge post-waking; independent predictor of HPA activation capacity
Who would benefit from this test?
This test is ideal for health-conscious individuals experiencing chronic fatigue, mood changes, anxiety, sleep disturbance, or occupational stress. It benefits those with trauma history, anyone initiating stress-management or supplement protocols wanting objective tracking, and professionals in high-stress fields seeking preventive baseline assessment. Athletes and high-performers monitoring stress resilience also find significant value.
When should I order this test?
Order when experiencing:
- Persistent fatigue unrelieved by sleep
- Elevated anxiety or depressed mood
- Difficulty concentrating or brain fog
- Frequent illness or low immune resilience
- Sleep problems or non-restorative sleep
Also ideal during lifestyle interventions (e.g., meditation programs, exercise regimens, supplementation) to objectively verify efficacy
Collection guidelines for accurate results
- Schedule testing on a typical, routine day
- Avoid days with acute stressors
- Ensure a normal night of sleep prior to collection
- Use results as a true baseline for comparison and follow-up assessment
How do I interpret the results?
Your results include a graphical cortisol curve overlaid on normal range bands, showing cortisol levels at each collection point. A normal pattern shows cortisol peaking 30-45 minutes after waking (50% above baseline), then progressively declining throughout the day, reaching lowest point at bedtime.
Abnormal patterns include:
- Blunted/flat CAR + elevated daytime cortisol: Chronic stress or burnout with HPA axis over-responsiveness
- Elevated morning + rapid decline: Acute stress or fatigue response
- Elevated, flat throughout day: HPA hyperactivation (depression, anxiety)
- Low morning + flat: HPA hypoactivation (burnout, exhaustion)
Elevated evening cortisol is the strongest predictor of sleep disruption and insomnia.
Discuss findings with your healthcare provider before modifying treatment or starting new interventions.
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
Scheduling considerations
- Choose a normal day without illness, injury, or major life events that can acutely elevate cortisol
Sleep
- Obtain 7–9 hours of sleep the night before
- Avoid sleep deprivation, which can significantly distort results
Medications and supplements
- Continue all medications and supplements as prescribed
- ZRT reference ranges are adjusted for common therapies
Day-of collection guidelines
- Limit caffeine to morning hours only (caffeine elevates cortisol for several hours)
- Avoid alcohol for 48 hours prior to collection
- Eat a normal, balanced breakfast
- Stay well-hydrated
- Avoid strenuous exercise within 4 hours of the first morning sample
First morning saliva collection
- Collect immediately upon waking
- Do not eat, drink, or brush teeth for at least 5 minutes prior to collection
How often should I get tested?
For initial assessment: One baseline test establishes your cortisol pattern.
For intervention monitoring:
- 8-12 weeks after starting lifestyle modifications (exercise, meditation, sleep changes) or supplementation
- Then annually for preventive monitoring in asymptomatic high-risk individuals
- Repeat testing at 8-12 week intervals during stress-management protocols to objectively verify efficacy
Why early detection matters
Sixty-six percent of U.S. workers report moderate-to-high burnout; 8.3% experience major depression; 3.6% have PTSD in any given year. All are scientifically linked to cortisol dysregulation. Early detection via home cortisol testing enables rapid lifestyle intervention (exercise, meditation, sleep hygiene, supplementation) before escalated clinical intervention becomes necessary. Studies show these modifications normalize cortisol within 6-8 weeks with effect sizes comparable to pharmaceutical interventions for mild-to-moderate HPA dysfunction. Objective baseline testing prevents unnecessary medication escalation and empowers informed prevention.
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