Cortisol
Why This Cortisol Blood Test Matters
This Cortisol Blood Test uses a professional venous blood sample taken by a qualified nurse at your home to measure your cortisol levels accurately, helping to diagnose hormone imbalances, check adrenal health, and better understand symptoms such as chronic fatigue, unexplained weight changes, persistent anxiety, or mood swings that may be linked to stress or adrenal conditions like Cushing’s syndrome or Addison’s disease.
What Is A Cortisol Blood Test?
A Cortisol Blood Test measures the level of cortisol hormone in your bloodstream, which is produced by your adrenal glands in response to stress, low blood sugar, and other physiological triggers. Cortisol plays a vital role in regulating metabolism, blood pressure, immune response, and your body’s stress reaction.
This test helps identify whether your cortisol levels are too high, too low, or fluctuating abnormally throughout the day. High cortisol can be linked with conditions like Cushing’s syndrome, chronic stress, or prolonged steroid use, while low cortisol may indicate Addison’s disease, adrenal insufficiency, or hypopituitarism.
Because cortisol levels naturally peak in the early morning and decline throughout the day, the timing of your blood sample is critical for accurate interpretation. Our nurse visit is typically scheduled for the morning to capture your peak cortisol level, providing the most clinically useful information for you and your GP.
What This Cortisol Blood Test Includes
This Cortisol Blood Test is a focused hormone assessment that measures your cortisol levels using a single venous blood sample taken by a qualified nurse at your home. Unlike multi-panel tests, this test is specifically designed to evaluate adrenal function and stress hormone balance.
The test provides a precise measurement of cortisol concentration in your blood at the time of sampling, which is then compared against established reference ranges to determine whether your adrenal glands are producing too much, too little, or a normal amount of this critical hormone.
Cortisol (Serum Cortisol)
Cortisol is the primary stress hormone produced by the adrenal glands, located just above your kidneys. It plays essential roles throughout your body, including regulating blood sugar, blood pressure, inflammation, metabolism, and the sleep-wake cycle.
- Normal morning cortisol range: Typically 140–690 nmol/L (levels are highest in the early morning, around 7–9 AM, and decline throughout the day).
- High cortisol: May indicate Cushing’s syndrome, chronic stress, depression, obesity, or prolonged use of corticosteroid medications.
- Low cortisol: May suggest Addison’s disease, adrenal insufficiency, hypopituitarism, or sudden withdrawal from long-term steroid therapy.
- Abnormal fluctuation: Can indicate disrupted circadian rhythm, shift work sleep disorder, or other hormonal imbalances affecting adrenal function.
Why Morning Testing Is Important
Cortisol levels naturally follow a circadian rhythm, peaking in the early morning shortly after waking and gradually declining throughout the day to reach their lowest point around midnight. For this reason, most cortisol blood tests are taken in the morning (typically between 7 AM and 9 AM) to capture the peak level, which provides the most clinically useful baseline for comparison.
If your GP suspects a specific adrenal condition, they may request additional afternoon or evening samples to assess the full daily pattern of cortisol secretion, but a single morning test is usually sufficient for initial screening and diagnosis.
What This Test Does Not Include
This test measures cortisol only and does not assess other hormones such as ACTH (adrenocorticotropic hormone), aldosterone, or DHEA, which may be required for more detailed adrenal or pituitary investigation. If your results suggest an adrenal disorder, your GP may recommend follow-up tests to confirm the diagnosis and identify the underlying cause.
For a broader hormone profile, you may want to consider our Female Hormone Blood Test or Male Hormone Blood Test, which include cortisol alongside other reproductive and stress-related hormones for a more comprehensive assessment.
Key Benefits Of Our Cortisol Blood Test
This Cortisol Blood Test combines clinical accuracy with the convenience of a home nurse visit, helping you gain clarity on your stress hormone levels and adrenal health without the need for clinic appointments or waiting rooms.
Accurate Diagnosis Of Hormonal Imbalances
Cortisol imbalances can cause vague symptoms such as fatigue, weight changes, and mood disturbances that overlap with many other conditions. A precise cortisol measurement helps your GP distinguish between adrenal disorders, chronic stress, depression, and other causes, leading to faster and more accurate diagnosis and treatment.
Early Detection Of Adrenal Conditions
Conditions like Cushing’s syndrome and Addison’s disease can develop gradually over months or years, with symptoms that are easy to dismiss as “just stress” or “getting older.” Testing your cortisol levels early can identify these conditions before they cause serious complications such as diabetes, osteoporosis, or adrenal crisis.
Convenient Morning Nurse Visit At Home
Because cortisol levels peak in the early morning, timing is critical for accurate results. Our qualified nurse visits your home at the optimal time (typically 7–9 AM) to collect your blood sample, eliminating the stress and inconvenience of rushing to a clinic first thing in the morning.
Professional Venous Sample For Reliable Results
Unlike finger-prick tests that can be affected by sample quality issues, our nurse takes a venous blood sample from your arm, providing a high-quality specimen that reduces the risk of inaccurate results or the need for repeat testing.
Clear, GP-Shareable Results
Your cortisol level is presented in a clear PDF report with reference ranges and clinical context, making it easy to share with your NHS or private GP for interpretation and next steps. Your GP can use these results alongside your symptoms and medical history to guide treatment decisions.
Supports Stress Management And Lifestyle Changes
If your cortisol levels are elevated due to chronic stress rather than a medical condition, your test results can serve as a powerful motivator to prioritize stress management techniques such as mindfulness, exercise, sleep improvement, and work-life balance adjustments.
Flexible For Monitoring And Follow-Up
If you are already being treated for an adrenal condition, taking cortisol-suppressing medication, or making lifestyle changes to manage stress, repeat testing every 3–6 months can help you and your GP track progress and adjust your treatment plan as needed.
Who This Cortisol Blood Test Is For
A Cortisol Blood Test is useful for anyone experiencing symptoms that may be linked to stress hormone imbalances or adrenal dysfunction. It is particularly valuable for people whose work, lifestyle, or health conditions make them more susceptible to cortisol dysregulation.
People With Chronic Stress Or High-Pressure Jobs
If you work in demanding roles such as healthcare, emergency services, finance, law, or management, prolonged stress can keep your cortisol levels elevated, increasing your risk of burnout, anxiety, sleep problems, and metabolic issues. Testing can confirm whether your stress is affecting your hormone levels and help you prioritize stress management.
Shift Workers And Those With Disrupted Sleep Patterns
Night shifts, rotating schedules, and irregular sleep patterns can disrupt your natural cortisol rhythm, leading to fatigue, weight gain, mood changes, and increased risk of chronic diseases. A cortisol test can reveal whether your circadian rhythm is out of sync and guide interventions to restore balance.
People Experiencing Unexplained Fatigue Or Weakness
If you feel persistently tired despite adequate rest, or if you struggle with muscle weakness and low stamina, low cortisol levels (adrenal insufficiency) could be the cause. This test helps distinguish adrenal fatigue from other causes of tiredness such as anaemia, thyroid problems, or sleep disorders.
Individuals With Unexplained Weight Changes
High cortisol can cause weight gain, particularly around the abdomen, face, and upper back, while also thinning the arms and legs. Low cortisol can lead to unintentional weight loss. If you are experiencing weight changes that do not match your diet or activity levels, testing your cortisol can provide important clues.
People With Mood Disturbances Or Anxiety
Cortisol imbalances can contribute to anxiety, irritability, depression, and emotional instability. If you are struggling with mood symptoms that have not responded well to standard treatments, checking your cortisol levels can help identify whether a hormonal imbalance is playing a role.
Those Taking Long-Term Corticosteroid Medications
If you take steroid medications such as prednisolone for conditions like asthma, inflammatory bowel disease, or autoimmune disorders, long-term use can suppress your adrenal glands. Cortisol testing is important when tapering off steroids to check whether your adrenal function has recovered.
People With A Family History Of Adrenal Or Pituitary Disorders
If close relatives have been diagnosed with Cushing’s syndrome, Addison’s disease, or pituitary tumours, you may have a higher risk of developing similar conditions. Regular cortisol screening can provide early warning and peace of mind.
Athletes And Fitness Enthusiasts
Intense training, calorie restriction, and overtraining can disrupt cortisol levels, leading to poor recovery, fatigue, injury, and hormonal imbalances. Monitoring your cortisol can help you optimize your training load and avoid overtraining syndrome.
How To Choose The Right Hormone Blood Test
Hormone testing can be complex, and it is important to choose the right test based on your symptoms, health goals, and what you want to investigate. Use this guide to decide whether a standalone Cortisol Blood Test is right for you, or whether a broader hormone panel would be more appropriate.
When A Cortisol Blood Test Is The Best Choice
- You have symptoms specifically linked to stress or adrenal function, such as chronic fatigue, unexplained weight changes, or mood disturbances.
- Your GP has suggested checking your cortisol levels based on your symptoms or medical history.
- You take long-term corticosteroid medications and need to monitor your adrenal function.
- You want to assess whether chronic stress is affecting your hormone levels.
- You prefer a focused, single-marker test rather than a broader panel.
When A Broader Hormone Test May Be Better
In some situations, a more comprehensive hormone panel can provide a fuller picture of your hormonal health. Consider these alternatives:
- Female Hormone Blood Test: If you are experiencing symptoms such as irregular periods, fertility concerns, menopause symptoms, or suspected PCOS alongside stress symptoms, a female hormone panel that includes cortisol, oestrogen, progesterone, LH, FSH, and testosterone may be more useful.
- Male Hormone Blood Test: If you are a man with fatigue, low libido, mood changes, or suspected low testosterone alongside stress symptoms, a male hormone panel that includes cortisol, testosterone, LH, FSH, and SHBG can provide a more complete assessment.
- Thyroid Blood Test: If your symptoms overlap with thyroid dysfunction (fatigue, weight changes, mood issues, sensitivity to temperature), consider our Thyroid Blood Test which checks TSH, Free T4, and Free T3 alongside or instead of cortisol.
- Well Person Blood Test: This test gives you the information you need to have an informed conversation with your doctor about your stress hormone levels, adrenal function, and the best plan to support your health and wellbeing. For general health monitoring, you may also consider our General Health Blood Test alongside cortisol testing.
Questions To Ask Before You Book
To make sure you pick the right test first time, consider:
- Are my symptoms mainly related to stress, fatigue, and mood, or do I have other concerns such as reproductive health or thyroid issues?
- Has my GP already suggested specific tests or markers that should be checked?
- Do I have a family history of adrenal, pituitary, or other hormonal disorders?
- Am I taking medications that could affect my cortisol levels, such as steroids or hormonal contraceptives?
- How often do I want to repeat this test to track changes over time?
Combining This Test With Other Checks
Some people choose to pair a Cortisol Blood Test with other tests to build a more complete picture of their health. For example, you might combine cortisol testing with thyroid function tests, vitamin D, or full blood count if you have multiple symptoms or complex health concerns.
If you are unsure which test or combination of tests is most suitable for you, you can contact our team for guidance or discuss your options with your GP before booking.
Why Choose Blood Test UK For Your At-Home Cortisol Blood Test?
| Feature | Finger-Prick Kits | GP/NHS | Blood Test UK Cortisol Test |
|---|---|---|---|
| Sample Quality | ❌ Capillary (finger-prick) | ✅ Venous (arm draw in clinic) | ✅ Venous blood taken at home by qualified nurse |
| Morning Testing (Peak Cortisol) | ⚠️ Self-timed (may miss optimal window) | ⚠️ Clinic hours may not align with 7-9 AM peak | ✅ Nurse visit scheduled for optimal 7-9 AM window |
| Wait Time | ⚠️ 7-14 days including postage | ❌ 2-6 weeks for NHS appointment + results | ✅ Results in 2-3 days after sample collection |
| Convenience | ✅ Self-test at home | ❌ GP appointment + clinic visit during working hours | ✅ Nurse visits your home at a time that suits you |
| Sample Accuracy | ⚠️ Capillary samples can be affected by technique | ✅ Professional venous draw | ✅ Professional venous draw by qualified nurse |
| GP-Shareable Report | ⚠️ Varies by provider | ✅ NHS record integrated | ✅ Professional PDF report with reference ranges |
| Lab Accreditation | ⚠️ Varies by provider | ✅ NHS-accredited | ✅ UKAS ISO 15189-accredited laboratory |
| Clinical Context | ⚠️ Limited interpretation | ✅ GP reviews with medical history | ✅ Clear report designed for GP discussion |
Testing For A Cortisol Blood Test
If you are experiencing symptoms that may be linked to stress hormone imbalances or adrenal dysfunction, a Cortisol Blood Test at home is particularly useful if you:
- Are experiencing chronic fatigue or persistent weakness that does not improve with rest.
- Have noticed unexplained weight changes, particularly weight gain around the abdomen or unintentional weight loss.
- Are dealing with mood disturbances such as anxiety, depression, irritability, or emotional instability.
- Have muscle weakness, joint pain, or changes in blood pressure that cannot be explained by other conditions.
- Take long-term corticosteroid medications and need to monitor your adrenal function.
- Work in high-stress environments or have experienced prolonged periods of intense stress.
- Have a family history of adrenal or pituitary disorders such as Cushing’s syndrome or Addison’s disease.
- Are experiencing symptoms that overlap with thyroid problems, diabetes, or other hormonal conditions and need to rule out cortisol imbalance.
Because cortisol symptoms can be vague and overlap with many other conditions, a blood test is the most reliable way to confirm whether your adrenal glands are producing too much, too little, or a normal amount of cortisol, helping you and your GP plan appropriate next steps.
How Often Should I Have A Cortisol Blood Test?
The ideal frequency depends on your symptoms, medical conditions, and treatment goals:
- First-time screening: If you have symptoms that may be linked to cortisol imbalance, start with a single morning test to establish your baseline cortisol level.
- Follow-up after abnormal results: If your initial test shows abnormally high or low cortisol, your GP may recommend repeat testing or additional investigations such as ACTH stimulation tests or 24-hour urine cortisol collections.
- Monitoring during treatment: If you are being treated for an adrenal condition or tapering off long-term steroid medications, your GP may recommend regular cortisol testing every 3-6 months to track your response to treatment.
- Stress management tracking: If you are making lifestyle changes to manage chronic stress, testing every 6-12 months can help you see whether your interventions are lowering your cortisol levels.
- Athletes and high-performance individuals: If you train intensively or work in demanding roles, annual or bi-annual cortisol testing can help you monitor for overtraining or burnout.
Note: These are general guidelines. Your GP or endocrinologist may recommend a different testing schedule based on your symptoms, medical history, and treatment plan.
Can I Use These Results With My GP?
Yes. Your cortisol test results are provided as a professional laboratory report in a format suitable for sharing with NHS or private GPs, endocrinologists, or other healthcare professionals. The report includes all necessary technical information and reference ranges used in UK clinical practice.
What Your Report Includes:
Cortisol level measurement showing your serum cortisol concentration at the time of sampling, measured in nmol/L (nanomoles per litre).
Clear reference ranges indicating whether your cortisol level falls within the normal range for the time of day your sample was taken.
Laboratory accreditation details confirming the test was analysed in a UKAS ISO 15189-accredited laboratory to the same standards used in NHS and private healthcare.
Easy-to-understand format designed for both you and healthcare professionals, so you can quickly identify any abnormalities and prepare for a focused discussion with your GP.
Important To Remember:
Only a qualified healthcare professional who knows your full medical history and symptoms can diagnose adrenal disorders or other hormonal conditions.
Your GP will interpret your cortisol results alongside your symptoms, medication history, physical examination findings, and potentially other tests such as ACTH stimulation tests or 24-hour urine cortisol collections.
A single abnormal cortisol result does not always mean you have a serious medical condition. Cortisol levels can be temporarily affected by acute stress, illness, certain medications, or the timing of your blood sample.
If your cortisol level is significantly abnormal, your GP may recommend follow-up testing, referral to an endocrinologist, or further investigations to determine the underlying cause.
If you have severe symptoms such as sudden severe weakness, fainting, confusion, severe abdominal pain, or signs of adrenal crisis, seek urgent medical attention immediately rather than waiting for routine blood test results.
This test gives you the information you need to have an informed conversation with your doctor about your stress hormone levels, adrenal function, and the best plan to support your health and wellbeing.
Nurse appointments fill up fast — book now to secure your preferred date.
Other Questions
- Fatigue
- Weight changes
- Mood disturbances
- Muscle weakness
- Changes in blood pressure
This blood test is to check on:
- Cortisol
For best results, take the test first thing in the morning (due to cortisol levels being highest then).
Collection method: Venous blood
Results available: 1-2 days after the sample has reached the laboratory.
Cortisol
A cortisol blood test measures the level of cortisol which is a hormone made by your adrenal glands. A cortisol blood test helps assess your body’s stress response and adrenal health, and can uncover hormone imbalances that affect your overall well being.
Evidence Behind Our Cortisol Testing
Our at-home Cortisol Blood Test service is aligned with UK clinical guidelines and international laboratory standards, ensuring your results are suitable for supporting diagnosis and treatment decisions related to adrenal function and stress hormone imbalances.
- Cortisol Testing For Adrenal Function:
UK and international guidance recommends serum cortisol testing as a first-line investigation for suspected adrenal disorders such as Cushing’s syndrome and Addison’s disease. Morning cortisol levels (7-9 AM) are the most reliable initial screening tool, with levels above 690 nmol/L suggesting excess cortisol and levels below 140 nmol/L indicating potential adrenal insufficiency.
(Source: NHS Addison’s disease information, NHS Cushing’s syndrome guidance) - Importance Of Morning Testing:
Cortisol levels follow a circadian rhythm, peaking in the early morning (typically between 7 AM and 9 AM) and declining throughout the day. Clinical guidelines emphasize that morning cortisol samples provide the most useful diagnostic information, as abnormally high or low morning levels are more clinically significant than afternoon or evening measurements.
(Source: NICE guidance on adrenal insufficiency) - Venous Blood Sampling For Accuracy:
Venous blood collection provides sufficient sample volume and consistent quality for laboratory hormone analysis, reducing the risk of sample errors and the need for repeat testing compared with capillary finger-prick samples. This is particularly important for cortisol testing where accurate timing and sample quality are critical.
(Source: UK laboratory guidance on blood sample collection) - Cortisol And Stress-Related Health Conditions:
Chronic elevation of cortisol is associated with increased risk of obesity, type 2 diabetes, cardiovascular disease, osteoporosis, and mental health conditions. Early detection and management of cortisol imbalances through testing and lifestyle interventions can help reduce these long-term health risks.
(Source: NHS stress and health guidance) - Laboratory Quality And Accreditation:
ISO 15189 is the international standard for medical laboratories covering sample handling, testing protocols and result reporting. Using UKAS ISO 15189-accredited labs helps ensure your cortisol test results are reliable, traceable and suitable for clinical decision-making.
(Source: UKAS medical laboratory accreditation, RCPath ISO 15189 overview)
These guidelines and standards shape how we design our Cortisol Blood Test, schedule morning nurse visits, and partner with UKAS ISO 15189-accredited laboratories, so your results are produced to the same quality benchmarks used for decision-making in NHS and private healthcare settings.
Preparing For Your Cortisol Blood Test
A Cortisol Blood Test requires minimal preparation, but following a few simple guidelines can help ensure accurate results and a smooth nurse visit.
- Schedule Your Test For The Morning – Cortisol levels are highest between 7 AM and 9 AM, so your nurse visit will typically be scheduled during this window to capture your peak cortisol level. This is the most clinically useful time for testing.
- No Fasting Required – You can eat and drink normally before your cortisol test. Cortisol levels are not significantly affected by food intake.
- Take Your Usual Medications – Continue taking your regular medications unless your GP specifically advises otherwise. If you take corticosteroids (such as prednisolone or hydrocortisone), let your GP know, as these will affect your results.
- Avoid Intense Stress Or Exercise Before Testing – Try to keep your morning calm and avoid vigorous exercise, arguments, or stressful situations immediately before your blood draw, as acute stress can temporarily elevate cortisol levels.
- Get A Good Night’s Sleep – Poor sleep can affect cortisol levels, so aim for a restful night before your test to ensure your results reflect your typical hormone pattern.
- Inform Your Nurse Of Any Medical Conditions – Let your nurse know if you have any bleeding disorders, are taking blood-thinning medications, or have any concerns about the blood draw.
- Wear Comfortable Clothing – Choose something with sleeves that can be easily rolled up so the nurse can access your arm for the venous blood sample.
If you have any questions about preparing for your Cortisol Blood Test, your nurse can provide guidance at the time of booking or during your appointment.
How it Works
Read about Fingerprick VS Venous blood sample 
1. Order a Test
Order your test, and then Answer the Questions about why you’re taking that test.
Our nurse will contact you for dates, so they can take your blood sample at your home.
Our nurse will then send your sample to our laboratory.
2. Our laboratory team run the tests
Our skilled laboratory staff conduct your blood tests in a clean and secure environment, ensuring accuracy and reliability.
Each test follows strict protocols to maintain the highest quality standards.
3. Receive Your Results within 7 days
We will email you to inform you that your blood test results are ready.
The email will have a PDF report attached, sent directly to your inbox.
4. Monitor your levels over time
With regular ongoing tests and reports, you can track your results. The reports can be shared with your GP.
Check if you’re improving healthily or where changes could be made.
Understanding Your Cortisol Blood Test Results
Your cortisol blood test results will show measured cortisol levels alongside established reference ranges. Morning cortisol levels are tested because cortisol follows a natural daily rhythm, peaking shortly after waking (7-9 AM). Here’s a guide to interpreting your results:
| Marker | Low Level | Normal Range | High Level |
|---|---|---|---|
| Morning Cortisol (7-9 AM) | Below 140 nmol/L May indicate: Adrenal insufficiency (Addison’s disease), pituitary problems, chronic fatigue. Symptoms: Extreme tiredness, weakness, low blood pressure, dizziness, weight loss, salt cravings |
140-700 nmol/L Healthy adrenal function with normal stress response |
Above 700 nmol/L May indicate: Cushing’s syndrome, chronic stress, depression, adrenal tumours, or medication effects (steroids). Symptoms: Weight gain (especially belly/face), high blood pressure, mood changes, sleep problems, muscle weakness |
| Afternoon Cortisol (if tested) | Below 80 nmol/L Expected natural decline, but very low levels may suggest adrenal insufficiency |
80-350 nmol/L Normal afternoon cortisol should be lower than morning levels |
Above 350 nmol/L Failure to decline normally may indicate chronic stress or Cushing’s syndrome |
Important: Reference ranges can vary slightly between laboratories and by time of day. Your results should always be interpreted by a qualified healthcare professional in the context of your symptoms, medical history, current medications (especially steroids), and clinical examination. A single abnormal cortisol result doesn’t necessarily confirm a disease—it may require repeat testing, further investigation (such as ACTH stimulation test, dexamethasone suppression test, or 24-hour urinary cortisol), and specialist endocrinology review.
What Your Cortisol Results Mean
- Low morning cortisol (below 140 nmol/L): Requires urgent medical review as it may indicate adrenal insufficiency (Addison’s disease), which can be life-threatening if untreated. Your GP may arrange an ACTH stimulation test to confirm diagnosis. Treatment typically involves hydrocortisone replacement therapy and medical alert bracelet.
- High morning cortisol (above 700 nmol/L): May indicate Cushing’s syndrome, chronic stress, depression, or recent steroid use. Your GP may arrange further tests including late-night salivary cortisol, 24-hour urinary free cortisol, or dexamethasone suppression test. Management depends on the underlying cause—stress management, medication review, or endocrinology referral.
- Normal cortisol with persistent symptoms: If your cortisol levels are normal but you still experience symptoms of high stress (anxiety, sleep problems, weight gain) or low cortisol (fatigue, weakness), discuss with your GP. You may benefit from 24-hour cortisol rhythm testing (four samples throughout the day) or salivary cortisol testing to detect subtle abnormalities.
- Borderline results (130-150 or 680-720 nmol/L): May require repeat testing at the same time of day, ideally when you’re feeling unwell for low results, or under standardized conditions for high results. Stress on the day of testing (including the stress of the blood draw itself) can temporarily elevate cortisol.
Factors That Can Affect Your Cortisol Results
- Time of day: Cortisol levels naturally peak in the morning (7-9 AM) and decline throughout the day, reaching lowest levels around midnight. Results must be interpreted according to collection time.
- Stress and anxiety: Acute stress (including anxiety about the blood draw itself) can temporarily raise cortisol levels by 20-30%. This is why repeat testing may be needed.
- Medications: Corticosteroids (prednisolone, dexamethasone, inhaled steroids for asthma), the contraceptive pill, and some psychiatric medications can affect cortisol levels and test interpretation.
- Sleep deprivation: Poor sleep or shift work can disrupt normal cortisol rhythm, potentially causing falsely elevated or blunted morning cortisol.
- Illness and inflammation: Acute illness, infection, or surgery can temporarily increase cortisol levels as part of the body’s stress response.
- Exercise: Intense exercise shortly before testing can raise cortisol levels. Avoid strenuous activity on the morning of your test.
Cortisol Blood Test FAQs
What Is A Cortisol Blood Test?
A Cortisol Blood Test measures the level of cortisol hormone in your bloodstream. Cortisol is produced by your adrenal glands and plays a vital role in regulating stress response, metabolism, blood pressure, and immune function. The test helps identify whether your cortisol levels are too high, too low, or fluctuating abnormally.
Why Is Morning Testing Important For Cortisol?
Cortisol levels naturally peak in the early morning (between 7 AM and 9 AM) and decline throughout the day. Morning testing captures your peak cortisol level, which provides the most clinically useful information for diagnosing adrenal disorders. Abnormally high or low morning cortisol is more diagnostically significant than afternoon or evening measurements.
Do I Need To Fast Before A Cortisol Blood Test?
No. You can eat and drink normally before your cortisol test. Cortisol levels are not significantly affected by food intake, so fasting is not required. However, you should try to avoid intense stress or vigorous exercise immediately before your test, as these can temporarily elevate cortisol levels.
How Is The Cortisol Blood Sample Taken?
A qualified nurse visits your home in the morning (typically between 7 AM and 9 AM) and takes a venous blood sample from a vein in your arm, similar to a standard hospital or GP blood test. This method provides a high-quality sample that reduces the risk of inaccurate results.
Where Is My Cortisol Sample Analysed?
Your sample is sent to a UKAS ISO 15189-accredited laboratory that follows recognised protocols for hormone analysis. Using accredited laboratories ensures reliable results, consistent reference ranges, and reports that your NHS or private GP can use to support diagnosis and treatment decisions.
How Long Will It Take To Get My Cortisol Results?
Results are typically available within 1-2 days of your sample reaching the laboratory. You will receive a clear PDF report by email, which you can download, save, and share with your GP or endocrinologist for interpretation and next steps.
How Often Should I Have A Cortisol Blood Test?
The frequency depends on your symptoms and medical situation. For initial screening, one morning test is usually sufficient. If results are abnormal, your GP may recommend follow-up testing. If you are being treated for an adrenal condition or managing chronic stress, testing every 3-6 months can help track your progress.
Can I Use These Results With My NHS Or Private GP?
Yes. Your cortisol results are provided in a professional laboratory format with reference ranges suitable for UK clinical practice, so they can be shared with NHS or private GPs, endocrinologists and other healthcare professionals. Your GP will interpret the results alongside your symptoms and medical history.
What If My Cortisol Results Are Abnormal?
If your cortisol level falls outside the normal range, this does not always mean you have a serious medical condition. Your GP will interpret your results in the context of your symptoms, medical history, medications, and the timing of your sample. They may recommend follow-up testing, referral to an endocrinologist, or further investigations to confirm the diagnosis.
Is This Test A Substitute For Seeing A GP?
No. A Cortisol Blood Test is a diagnostic tool that provides valuable information about your hormone levels, but it does not replace medical advice. Only a qualified healthcare professional who knows your full medical history and symptoms can diagnose adrenal disorders and recommend treatment.
