Reviewed by The Wellness Team.
Feeling wired, exhausted and unable to switch off sends a lot of people searching for a cortisol test. The instinct is right in one way, your body is telling you something, but the honest answer about cortisol testing is more useful than the marketing.
This page explains what cortisol testing genuinely measures, when it matters, and which tests actually answer the questions most stressed and exhausted people are really asking.
What cortisol is and what a single test shows
Cortisol is your main stress hormone, released on a daily rhythm that peaks in the morning and falls through the day. A single blood cortisol reading captures one point on that curve, which is why a random afternoon level tells a doctor very little on its own.
Where cortisol testing genuinely matters is at the extremes. A doctor may arrange timed cortisol testing when the pattern of symptoms raises the possibility of the body making too little cortisol, as in Addison's disease, or too much, as in Cushing's syndrome. Both are uncommon, both are serious, and both are exactly the sort of thing a proper assessment is designed to catch or confidently exclude.
What a single cortisol level cannot do is measure how stressed you are. There is no blood test that grades everyday psychological stress, and any clinic selling one as a stress score is selling you a number without meaning.
The tests that answer the real questions
To book or ask a question, message WhatsApp or call 020 3951 3429.
Most people asking about cortisol are actually asking why they feel the way they do. Tired despite sleep, gaining weight around the middle, poor concentration, low mood, feeling constantly on edge. Those symptoms deserve proper investigation, and the useful panel is usually the fatigue and metabolism workup rather than cortisol alone.
Thyroid function, because an underactive thyroid produces almost exactly this picture. Full blood count and ferritin, because anaemia and low iron stores are common and correctable. HbA1c and glucose, because blood sugar swings drive fatigue and weight change. B12 and vitamin D, because deficiencies are widespread and treatable. Our guide to the blood tests that explain tiredness covers each marker in detail.
Where a consultation earns its place
The pattern of your symptoms, your sleep, your working hours and your history decides which tests are worth running. A consultation first means you pay for the right bloods once, rather than a blanket panel that answers nothing. A video consultation is usually enough to plan the workup, and bloods can then be arranged through our blood test referral route.
A telephone consultation is £59, a video consultation £150 and an in-person GP consultation £220. Blood test pricing is confirmed against the exact panel before anything is drawn.
To talk to a doctor, message WhatsApp, call 020 3951 3429 or email team@thewellnesslondon.com.
Questions people ask
Can a blood test measure my stress levels?
Not directly. Cortisol follows a daily rhythm and responds to sleep, illness, time of day and medication, so a single reading cannot grade how stressed you feel. Testing cortisol is valuable when a doctor suspects the body is making too little or too much of it. For everyday stress and fatigue, the useful answers come from thyroid, iron, blood sugar and vitamin testing alongside a proper history.
When is cortisol testing actually needed?
When the symptom pattern suggests a disorder of cortisol production. That includes unexplained weight loss with darkening skin and low blood pressure at one extreme, or central weight gain with easy bruising, muscle weakness and high blood pressure at the other. If a doctor suspects either, timed cortisol tests and sometimes stimulation testing are arranged properly.
What tests should I have if I feel burnt out?
Start with thyroid function, a full blood count, ferritin, HbA1c, B12 and vitamin D, alongside a consultation that covers sleep, mood and workload. That combination finds the common correctable causes of burnout-type symptoms, and it is the workup our doctors reach for before anything more exotic.
How much does testing cost?
A consultation to plan the right tests is £59 by telephone, £150 by video or £220 in person. The blood panel is priced against exactly what is being tested and confirmed before anything is drawn, so there are no surprises.