Test ID: S-120 | Sample Type: Saliva | Technology: LC-MS/MS | Results Time: 3–5 Working Days After Laboratory Receives Sample | Laboratory: ZRT Laboratory – CLIA Certified | Hormone Specialist Doctor Interpretation: Included | Suitable For: Adults and Children
What Does This Test Measure?
Saliva — 4-Point Cortisol Profile (LC-MS/MS): Morning Cortisol, Noon Cortisol, Evening Cortisol, Night Cortisol.
4 markers — the complete daily adrenal rhythm for assessing the full cortisol curve, HPA axis function, and cortisol–testosterone interaction across the entire day in a single at-home saliva kit.
Related Symptoms
Persistent fatigue or exhaustion that sleep does not resolve, difficulty waking or feeling unrefreshed in the morning, afternoon energy crashes, heavy reliance on caffeine, insomnia or night waking, low libido or erectile dysfunction, loss of muscle mass or poor gym recovery, unexplained abdominal fat gain, anxiety, irritability, low mood, brain fog, chronic stress or burnout, or symptoms of low testosterone with inconclusive standard blood results.
Did You Know?
A single morning cortisol reading identifies only one phase of the daily adrenal rhythm. For men, the clinically critical questions are: is cortisol suppressing testosterone synthesis during the day via pregnenolone steal? Is elevated evening cortisol preventing the testosterone and growth hormone surge that occurs in early sleep? Is high night cortisol destroying the deep sleep phases responsible for 70% of daily testosterone production? None of these questions can be answered by a single time point — they require the full four-point curve. The 4-point profile is the minimum required to identify which phase of the day is driving androgenic suppression, insulin resistance, visceral fat accumulation, or adrenal burnout.
Who Should Consider This Test?
- Persistent fatigue or exhaustion that sleep does not resolve
- Difficulty waking in the morning or feeling unrefreshed despite adequate sleep
- Afternoon energy crashes or heavy reliance on caffeine to function
- Insomnia, night waking, or inability to switch off at bedtime
- Low libido or reduced sexual interest
- Erectile dysfunction or reduced sexual performance
- Loss of muscle mass or poor recovery after training
- Unexplained abdominal fat gain despite exercise
- Anxiety, irritability, or low mood
- Brain fog, poor focus, or reduced motivation
- Symptoms of low testosterone with normal or inconclusive standard blood results
- Chronic stress, overtraining, or burnout
- Currently on TRT and wanting to understand cortisol’s impact on treatment response
- Men wanting to identify exactly which phase of the day is driving their symptoms
Why This Test Is Particularly Important for Men
- High morning cortisol acutely suppresses testosterone via pregnenolone steal and drives anxiety, elevated blood pressure, and poor recovery — a blunted morning cortisol signals adrenal burnout with profound fatigue and loss of drive
- Elevated noon or afternoon cortisol drives insulin resistance, visceral fat accumulation, and increased aromatase activity — converting testosterone to estradiol and compounding androgenic decline throughout the day
- High evening cortisol prevents the natural testosterone and growth hormone surge that occurs in the early stages of sleep — one of the most common and clinically overlooked drivers of low morning testosterone in men
- Elevated night cortisol directly suppresses the deep sleep phases during which the majority of daily testosterone is produced — causing insomnia, night waking, and chronically impaired testosterone synthesis regardless of total sleep duration
- A flat cortisol curve — seen in advanced burnout and chronic overtraining — is associated with total hormonal exhaustion and requires a different intervention to an elevated curve; the two patterns are indistinguishable from symptoms alone
Not Sure Which Test Is Right for You?
Email us at info@hormonelab.co.uk with your gender, age, symptoms, medications, and any current treatments. We will forward your enquiry to our doctors and respond within 24 hours.
How It Works
- Order your kit — delivered directly to your door
- Collect saliva at four time points: morning (within 30 minutes of waking, before 9am), noon, evening, and night — following the detailed instructions provided
- Post your samples to ZRT Laboratory using the return instructions provided
- Receive your full report by email within 3–5 working days
What You Receive
- All four cortisol readings with male-specific reference ranges
- Visual chart showing your complete daily cortisol rhythm curve
- Written interpretation by a Hormone Specialist PhD Doctor including cortisol–testosterone interaction assessment and phase-specific androgenic impact analysis
- Personalised next-step recommendations
- Laboratory fee included — no hidden charges
Why We Use ZRT Laboratory
All testing is performed by ZRT Laboratory — a globally recognised, CLIA-certified diagnostic laboratory founded in 1998 by Dr. David Zava, PhD. ZRT has performed over 11 million tests and is trusted by healthcare professionals in 96+ countries.
- Pioneers of at-home dried blood spot (DBS) and saliva hormone testing
- Advanced LC-MS/MS technology for clinical-grade accuracy
- Qualified for the CDC Hormone Standardization (HoSt) Program
- Personalised reference ranges based on age and sex
Through our partnership with ZRT Laboratory, Hormone Lab UK delivers internationally recognised, research-backed hormone testing to people across the UK and Europe — from the comfort of home.
Frequently Asked Questions
Why measure cortisol at four points rather than just the morning?
Each time point has distinct androgenic and metabolic consequences. Morning cortisol assesses the Cortisol Awakening Response and testosterone suppression risk; noon assesses insulin resistance and aromatase drive; evening assesses whether cortisol is preventing the testosterone surge in early sleep; night assesses whether deep-sleep testosterone synthesis is being suppressed. A single reading cannot identify which phase is responsible for a man’s symptoms.
Can I use this test if I am on TRT?
Yes. This test is particularly valuable for men on TRT wanting to understand whether cortisol dysregulation is undermining the effectiveness of their testosterone therapy or causing residual symptoms.
Do I need to fast before collecting?
No fasting is required. Collect each sample according to the time point instructions provided in your kit.
Should I start with just the morning cortisol test instead?
The morning test (SAL-CORT-AM) is an appropriate first step if your symptoms are primarily morning-focused. If you have symptoms across different parts of the day — afternoon crashes, evening anxiety, or night waking — the 4-point profile is the more appropriate assessment and avoids the need for a second test.
Does the price include the laboratory fee?
Yes. The full laboratory analysis fee is included. There are no additional charges. You are only responsible for posting your samples to the laboratory.
How long is the kit valid for?
The kit must be used within 12 months of the purchase date.
