What is Cortisol (serum)?
your stress hormone
Cortisol is the body's main stress hormone. The value is highest in the morning and varies through the day - it is therefore measured fasting, early in the morning.
A single value gives a snapshot but does not capture full adrenal function. A more complete picture requires saliva cortisol across the day.
Test facts
- Unit
- nmol/L
- Sample
- Serum
- Fasting
- No fasting needed
- Turnaround
- 2 days
What does low Cortisol (serum) mean?
Low morning cortisol can suggest adrenal insufficiency and should be investigated.
What does high Cortisol (serum) mean?
High cortisol can reflect stress, sleep deprivation, depression, or more rarely Cushing's syndrome.
Panels that measure Cortisol (serum)
- Hormone+
- Perimenopause
- Cortisol Snapshot
- Stress & Cortisol Basic
- Stress & Cortisol Full
- Athlete Performance
More markers in the same area
Launching in Stockholm in 2026.
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This is general information about the marker, not an assessment of your values and not medical advice. Last updated: May 2026.