Late-night salivary cortisol
What this test measures
Cortisol normally falls to its lowest point around midnight. A saliva sample collected at bedtime measures the free hormone at that low point, so a raised value points to a lost daily rhythm.
Why doctors request it
One of the screening tests for cortisol excess, and convenient because it is collected at home.
What commonly pushes it up
- Cortisol excess
- Shift work or a disturbed sleep pattern
- Smoking or chewing tobacco on the evening
- Blood in the sample from gum disease
- Steroid creams or inhalers used near the mouth
What commonly pushes it down
- The expected result is a low value
Everyday reasons for a value outside the range
- Sleep pattern, smoking and gum bleeding all affect it
- Method-dependent thresholds
About the sample
Collected between 11pm and midnight on two or more nights, without eating, smoking or brushing teeth for 30 minutes beforehand.
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Read my report freeThis is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.