Cortisol is your main stress hormone; testing helps check adrenal function and daily rhythm.
Cortisol is the body's main stress hormone, made by the adrenal glands. It helps control blood sugar, blood pressure, the immune system, and how the body handles stress.
Cortisol follows a daily rhythm, highest in the early morning and lowest late at night. A blood test usually measures total cortisol in serum, and the time of the draw matters a great deal.
Cortisol testing checks how well the adrenal glands and the systems that control them are working. Levels that are too high or too low can both cause problems and point to specific conditions.
Persistently high cortisol can suggest Cushing syndrome, while low levels can point to adrenal insufficiency. Because levels swing through the day, the result is always read together with the time it was taken.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
Typical adult guidance for serum cortisol, timing dependent:
| Time | Range |
|---|---|
| Morning (around 8am) | 140 to 690 nmol/L |
| Late afternoon | 80 to 330 nmol/L |
Ranges vary by assay and lab. A single value is interpreted with the collection time and your symptoms.
Stress, illness, pregnancy, and oestrogen-containing medicines can raise cortisol. Shift work and disrupted sleep alter the daily rhythm. Biotin supplements and some steroids can interfere with results.
Read alongside ACTH, and sometimes with a morning sample compared to evening, when assessing adrenal function.
What do my cortisol results mean in simple terms? They reflect how your adrenal glands respond to daily demands and stress. Your doctor considers timing, symptoms, and other tests to interpret them.
Do I need to fast for a cortisol test? No. Timing matters more; early morning or late-night sampling may be recommended.
What can affect my cortisol levels? Steroid medicines, birth control or estrogen, illness, stress, poor sleep, shift work, intense exercise, and pregnancy can change results.
How often should I test cortisol? Test when symptoms are present, after medication changes, or to monitor an abnormal result, as advised by your clinician.
How long do results take? Results are usually ready in about 7 days.
What should I discuss with my clinician? Share your symptoms, all medicines and supplements, sleep schedule, and ask if confirmatory tests like saliva, urine, or an ACTH stimulation test are needed.
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