Cortisol test: a sign of low testosterone or burnout?

Cortisol is a hormone made by your adrenal glands. It helps keep your blood sugar steady, helps regulate how your body responds to strain, and follows a strong day-night rhythm: high in the early morning, low around midnight.

Measuring cortisol is a real, recognised test. Doctors use it to detect two rare conditions: Cushing's syndrome (too much cortisol) and adrenal insufficiency, or Addison's disease (too little cortisol). These are serious illnesses, and for that question the test is essential.

But look at what the test actually involves. The Endocrine Society guideline prescribes: two late-night saliva samples, two 24-hour urine collections, or a dexamethasone suppression test where you take a tablet the night before. None of these is a blood draw you can simply walk in for. For Addison's disease, a morning blood draw between 06:00 and 10:00 is a legitimate first step, but only alongside ACTH, and only when a doctor already suspects the disease.

What the test is not: a gauge of how hard your life is, how hard you train, or how your testosterone is doing.

• Through your GP. If your GP suspects an adrenal disorder, they request the right test. For Cushing's syndrome the guideline names late-night saliva, 24-hour urine or a dexamethasone suppression test.
• With a saliva test at home. These kits are sold over the counter. Saliva cortisol swings even more than blood cortisol. A value has to change by 96 to 245% before the difference is real.
• With a blood draw, like this cortisol test. You do not need a referral from your GP. The blood is drawn at a location run by a partner laboratory. Plan the draw between 06:00 and 10:00, fasting.

Cortisol fluctuates enormously, even in healthy men doing nothing unusual. Clinical chemistry calls this the reference change value: how much a value must change before you can say with 95% confidence that something genuinely changed. For cortisol in blood, that is around 47%. For salivary cortisol it runs to 96 to 245%, depending on the time of day.

Put plainly: your cortisol has to roughly double before anyone can even establish that anything changed. Everything below that is noise. We could draw your blood twice, an hour apart, and get two numbers tens of percent apart, both entirely normal, and both meaningless.

On top of that, the things that shift your cortisol are precisely the things this audience brings with them:

• a heavy training session or an intense week at work shortly before the draw, temporarily pushing your value up
• night shifts, shifting bedtimes and too little sleep, which overturn the daily rhythm the test entirely depends on
• alcohol, which affects how your body regulates cortisol
• corticosteroids (prednisone, dexamethasone, including creams and inhalers), which suppress your own cortisol production
• the needle itself: the stress of a blood draw raises your cortisol at the very moment you measure it

So you are not measuring your "stress level". You are measuring where your cortisol happened to be when the needle went in.

A cortisol test does not answer that question.

The direction of the cortisol effect is not even settled. The largest meta-analysis in this field pooled 147 studies of the cortisol response on waking. What came out: with job stress that response goes up, while with burnout and exhaustion it goes down. Two opposite directions, in the same measurement, in people who both say they are spent.

And then the strongest study actually arguing for cortisol as a burnout marker. It found higher midday cortisol in burnout patients. Exactly the reverse of the story you read everywhere, which is that exhausted adrenals make less cortisol.

So one number cannot possibly separate "stressed" from "burned out" from "nothing is wrong". A systematic review of 31 burnout studies covering 38 different biomarkers summed it up: no potential biomarkers for burnout were found. Not one. Cortisol included.

The same goes for "adrenal fatigue", the term you meet next to almost every cortisol test on sale. That condition does not exist. The term was coined in 1998 by a chiropractor. A 2016 systematic review searched 3,470 publications, kept 58, and found no substantiation whatsoever. In most fatigued participants, the cortisol measurements were simply normal. The Endocrine Society is blunt: no scientific proof exists, and there is no test that can detect it.

This is not only wasted money. The supplements sold alongside it can cause harm. A study in Mayo Clinic Proceedings tested twelve over-the-counter "adrenal support" products: all twelve contained thyroid hormone that was not on the label, and a quarter contained a steroid. Taking adrenal hormones you do not need can suppress your own hormone production.

The testosterone-to-cortisol ratio (T:C) comes from sports science, where researchers used it to try to tell whether an athlete was becoming overtrained. It never became a clinical test, and there is a reason for that.

There is no validated cut-off. There is no number below which you have "a bad ratio", because nobody has ever shown what that number should be. There is also no outcome evidence: no study showing that men with a lower ratio are measurably worse off, or that anything useful changes if you try to steer it.

And then the arithmetic problem. A ratio inherits the noise of both numbers it is built from. Cortisol has to roughly double before you can say it changed at all. Testosterone has its own daily rhythm and varies from day to day as well. Divide one erratic number by another and you get a result that is even more erratic than either measurement on its own. You could have it done on two consecutive mornings and get two very different ratios, without a single thing having changed about you.

An "off T:C ratio" is therefore not a finding. It is a number you cannot act on, built on a measurement too noisy to build anything on.

If you are tired, your libido is gone and you are gaining weight, those are real symptoms, and often they have a real cause. It is just rarely in your cortisol. These are the questions that do matter:

• your sleep, and sleep apnoea above all. Snoring, waking with a dry mouth, dozing off during the day, a partner saying you stop breathing for a moment. Sleep apnoea is common in men, is often missed, and causes exactly this list: fatigue, low energy, less interest in sex
• alcohol, in both quantity and frequency
• your thyroid, a common and treatable cause of fatigue
• your iron stores
• low mood and depression, which in men often show up as fatigue, irritability and loss of libido rather than as sadness

If you want blood drawn, the Dutch primary-care diagnostics guidance (NHG/NVKC LESA Laboratoriumdiagnostiek) starts persistent fatigue with a short list. Short, and for a reason:

• Haemoglobin, and if abnormal your iron stores via ferritin
• CRP, an inflammatory marker
• Fasting glucose, to rule out diabetes
• TSH, your thyroid

And testosterone itself? Unlike cortisol, that is a test with a real protocol. The international guideline prescribes: drawn in the morning, fasting, and repeated if the result is low, and only interpreted alongside your symptoms by a doctor. We are not selling you a promise about what it will show. If your question is whether your testosterone is low, measure testosterone. That is a test with a pathway behind it. A one-off cortisol draw is not.

If you feel burned out, there is no blood value that demonstrates it. Burnout is a clinical diagnosis your GP makes from your story, and the Dutch guideline on work-related stress and burnout says of additional investigation, literally: "not indicated".

We would rather earn nothing from you than sell you a test that does not answer your question.

There genuinely are situations where measuring cortisol is exactly the right thing to do. If you recognise yourself here, you can order the test below:

• your GP or specialist asked for a cortisol measurement. Then you are here to have the test done, not to diagnose yourself, and we are glad to help
• you already have a known adrenal or pituitary condition and you are monitoring your values
• you use or have stopped corticosteroids (prednisone, dexamethasone, including creams and inhalers), where your own cortisol production may be suppressed. That is a legitimate reason for a doctor to want to see your cortisol

If you order without a doctor's request, book your draw between 06:00 and 10:00 in the morning, fasting and without heavy exertion beforehand. Outside that window your result cannot be compared against the correct reference range.

One thing holds even then: a single cortisol value is never a diagnosis. An abnormal result means your GP has to redo the work properly, with the right test.

We think you should be able to check what we base this on.

• Nieman LK et al. The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2008;93(5):1526-40. PMID 18334580. (Explicitly recommends against random serum cortisol.)
• Bornstein SR et al. Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2016;101(2):364-89. PMID 26760044. ("There is no evidence to support the use of random cortisol".)
• Chida Y, Steptoe A. Cortisol awakening response and psychosocial factors: a systematic review and meta-analysis. Biol Psychol. 2009;80(3):265-78. PMID 19022335. (147 studies; the response rises with job stress and falls with burnout and exhaustion.)
• Pilger A et al. Midday and nadir salivary cortisol appear superior to cortisol awakening response in burnout assessment and monitoring. Sci Rep. 2018;8(1):9151. PMID 29904183. (Burnout patients had higher midday cortisol.)
• Danhof-Pont MB, van Veen T, Zitman FG. Biomarkers in burnout: a systematic review. J Psychosom Res. 2011;70(6):505-24. PMID 21624574. (31 studies, 38 biomarkers: "No potential biomarkers for burnout were found".)
• Cadegiani FA, Kater CE. Adrenal fatigue does not exist: a systematic review. BMC Endocr Disord. 2016;16(1):48. PMID 27557747.
• Akturk HK et al. Over-the-Counter "Adrenal Support" Supplements Contain Thyroid and Steroid-Based Adrenal Hormones. Mayo Clin Proc. 2018;93(3):284-90. PMID 29502560.
• Bhasin S et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-44. PMID 29562364. (On diagnosis: fasting morning measurement, repeated if low.)
• Nijrolder I et al. Diagnoses during follow-up of patients presenting with fatigue in primary care. CMAJ. 2009;181(10):683-7. PMID 19858240.
• NHG/NVKC LESA Laboratoriumdiagnostiek. NHG-Standaard Overspanning en burn-out (M110): additional investigation "not indicated".