Cortisol levels are checked through a blood draw, a saliva sample, or a urine collection. Your doctor can order any of these, and saliva tests can even be done at home with a kit. The method your provider chooses depends on what they’re looking for and how your cortisol patterns need to be tracked throughout the day.
Three Ways Cortisol Is Tested
A blood test is the most common method. A healthcare professional draws blood from a vein in your arm, typically twice in the same day: once in the early morning (between 6 and 8 a.m.) when cortisol is naturally at its peak, and again around 4 p.m. when levels are much lower. Comparing those two numbers tells your provider whether your body is following a healthy pattern.
A saliva test can be done in a clinic or at home using a collection kit. Because it’s simple and painless, providers sometimes ask you to collect several samples at different times of day. This gives a fuller picture of how your cortisol rises and falls over a 24-hour cycle. Saliva testing for cortisol is considered highly reliable. Some endocrinology research has found that salivary cortisol measured by standard lab methods is actually preferable to blood cortisol for assessing how well the stress-hormone system is functioning.
A 24-hour urine test measures total cortisol output over an entire day. You’ll receive a special container and instructions: on day one, you urinate into the toilet first thing in the morning, then collect every drop of urine into the container for the next 24 hours. On day two, you add your first morning urine to the container, cap it, label it with your name and the date, and return it to the lab. The container needs to stay refrigerated or in a cool place the whole time. In some cases, a single morning urine sample is enough.
Why Timing Matters So Much
Cortisol isn’t steady throughout the day. It follows a predictable rhythm: levels are high when you wake up, peak about 30 to 60 minutes after waking, then gradually decline to their lowest point around bedtime. This daily curve is so consistent that deviations from it are one of the first signals something may be off with your adrenal function.
That’s why your provider specifies when to have your blood drawn or when to collect saliva. A cortisol reading of 15 mcg/dL at 7 a.m. is perfectly normal, but the same number at 4 p.m. would be unusually high. Normal morning levels (6 to 8 a.m.) fall between 10 and 20 mcg/dL. By late afternoon, healthy levels drop to 3 to 10 mcg/dL.
What Can Throw Off Your Results
Several things can temporarily spike cortisol and skew your test. Exercise is a significant one. Hard workouts, especially high-intensity interval training or long endurance sessions, cause a sharp cortisol surge as part of the body’s stress response. That spike is temporary, but if it coincides with your test window, it can inflate your numbers. Poor sleep the night before can do the same, as can acute anxiety, including the anxiety of getting your blood drawn.
Certain medications also interfere with results. Birth control pills, corticosteroid drugs (like prednisone or hydrocortisone creams), and antiseizure medications can all affect cortisol readings. Your provider may ask you to pause some of these before testing. The most important thing you can do before any cortisol test is give your provider a complete list of everything you’re taking, including supplements. You may also be asked to fast beforehand, depending on the test type.
When Providers Typically Order This Test
Doctors check cortisol levels when symptoms suggest your body is producing too much or too little of it. Too much cortisol over time can point to Cushing’s syndrome, which often shows up as unexplained weight gain (particularly around the midsection and upper back), round face, thinning skin that bruises easily, and muscle weakness. Too little cortisol may indicate Addison disease or secondary adrenal insufficiency, which can cause fatigue, unintended weight loss, darkened skin patches, low blood pressure, and salt cravings.
If you’ve already been diagnosed with one of these conditions, cortisol testing is also used to monitor how well treatment is working.
What Happens if Results Are Abnormal
A single abnormal cortisol reading doesn’t automatically mean you have a medical condition. Because so many factors influence cortisol, including stress, sleep, medications, and even the time you ate your last meal, your provider will usually want to confirm the result before drawing conclusions.
One common follow-up is the dexamethasone suppression test. You take a small dose of a synthetic steroid the night before, then have your blood drawn the next morning. In a healthy system, the medication signals your body to stop producing cortisol, and levels drop. If cortisol stays high despite the signal, it suggests something is overriding the body’s normal feedback loop. Before this test, you’ll need to share your full medication and health history, and you may be asked to stop certain drugs and avoid eating or drinking beforehand.
At-Home Cortisol Kits
Several companies sell saliva-based cortisol test kits directly to consumers. These typically involve collecting saliva samples at multiple points during the day (morning, midday, evening, and bedtime) and mailing them to a lab. The four-point salivary cortisol test has been used in integrative medicine for decades and is well-supported for measuring cortisol’s daily rhythm.
That said, an at-home kit gives you data without clinical context. A result that looks high or low on paper may be completely normal for your situation, or it may need follow-up testing that only a provider can order. If you go the at-home route, plan to bring your results to a doctor who can interpret them alongside your symptoms, medical history, and any medications you’re taking.