Late-night salivary cortisol
- Requires a medical indication
Late-night salivary cortisol collected at home over two nights. It assesses whether cortisol falls at the end of the waking period, as normally happens, and is one of the screening tests for Cushing's syndrome. It requires a medical indication and a stable sleep schedule to be interpreted.
Requires a medical prescription
Results in 5-7 working days
Saliva sample. Includes: Salivary cortisol. See what it measures
This test measures whether cortisol falls at night as it should, and it can only be interpreted properly within an assessment that a doctor has already started. Excess weight, polycystic ovary syndrome, alcohol consumption and some mood disorders raise cortisol by themselves, so a high result does not mean the same thing for everyone.
What it is for
It is used to investigate whether the night-time fall in cortisol has been lost, one of the changes that can occur in Cushing's syndrome. A saliva sample avoids the stress of a blood draw and allows the test to be repeated on two different nights.
It does not measure tiredness or everyday "stress" and does not identify the cause of a rise. An abnormal result needs confirmation and comparison with other tests chosen by the doctor.
When it is recommended
- Medical suspicion of Cushing's syndrome because of several progressive and consistent signs
- Monitoring of hypercortisolism that has already been diagnosed
- Follow-up after treatment for Cushing's syndrome
- When kidney function or a difficult urine collection makes the urine measurement less suitable
- It is not usually the best option with night work or very variable sleep schedules
Clinical comment
We have included two nights because cortisol is released in pulses and a single sample may not represent the usual pattern. Agreement between the two gives more confidence; if they disagree, the assessment may need to be repeated.
The collection time should be matched to sleep, not just to the clock. In someone who sleeps at night, the sample is taken at bedtime. In people who work shifts or change schedule often, the rhythm is shifted and the test becomes less reliable.
Bear in mind that alcohol, acute illness, intense exercise, some mood disorders and other situations can raise cortisol without Cushing's syndrome. Corticosteroid creams can also directly contaminate the collection device if they come into contact with the hands or mouth.
Dr. Antonio Mas
What is tested
• Salivary cortisol (two nights): Measures the free fraction of cortisol in two samples collected at the end of the waking period, when the level should be close to its daily low.
- Salivary cortisol (two nights)
How to prepare
Collect the samples at bedtime on two different nights. In the 15 minutes beforehand, do not eat, drink, smoke or brush your teeth. Follow the device and storage instructions provided by the partner centre.
Report any corticosteroid you use, including inhalers, creams and injections. Wash your hands well before handling the device to avoid contamination with creams.
You can add
Without another needle. It is offered when you order, so you do not have to decide now.
- General blood testA general blood test with full blood count, glucose, cholesterol and kidney and liver function: the basic parameters included in any general check-up.+€59.00
- General + nutritional blood testEverything in the general blood test (anaemia, kidneys, liver, cholesterol and glucose) plus iron stores, vitamin D, vitamin B12 and folic acid. It is the broadest add-on: it covers the general and the nutritional in one go.+€129.00
Related blood tests
We have other profiles in Other tests with more or fewer tests:
- Dexamethasone suppression test€39.00
- Basal blood cortisol€39.00
- 24-hour urine free cortisol€49.00
- High calcium, PTH and mineral metabolism€89.00
- Cortisol assessment, in saliva and urine€99.00
- High prolactin assessment€149.00
- Metabolic assessment of kidney stones (blood and 24-hour urine)€179.00
- Pituitary hormone profile€199.00
The most comprehensive is not always the most useful. If you are not sure, the one we recommend to start with is High prolactin assessment.
What it is based on
Pituitary Society · Lancet Diabetes Endocrinol 9(12):847-875
Consensus on diagnosis and management of Cushing's disease: a guideline update
This is where the figure comes from that makes this the recommended first test: sensitivity of 97% and specificity of 97.5%, compared with 81% and 81.5% for the other two, and the consensus also states in its text that late-night salivary cortisol is the most specific of the three. It asks for at least two or three samples, which is what is sold here, and names it as the preferred option when there is a kidney problem. The shift work exception is also theirs: with shifted sleep patterns it proposes the dexamethasone suppression test.
Endocrine Society · J Clin Endocrinol Metab 93(5):1526-1540
The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline
Places late-night salivary cortisol among the three accepted screening tests and writes the quantity into it: two measurements. With a single night, the test has not been done.
Protocol designed by Dr. Antonio Mas, specialist in Endocrinology and Nutrition, Spanish medical licence no. 080846289, and reviewed in September 2026.
This blood test is a standardised protocol and does not replace a medical consultation. If you have symptoms, a known condition or a complex clinical situation, speak to your doctor.