24-hour urine free cortisol
- Requires a medical indication
24-hour urine free cortisol test with two collections on different days. It is one of the accepted tests for investigating possible Cushing's syndrome and estimates the amount of free cortisol excreted over the day. It requires a medical indication and a complete collection for the result to be valid.
Requires a medical prescription
Results in 5-7 working days
24-hour urine sample. Includes: 24-hour urine free cortisol. See what it measures
This test only makes sense within an assessment that a doctor has already started. Ordered on its own, an abnormal result creates more investigations than it resolves: excess weight, polycystic ovary syndrome and alcohol consumption raise cortisol by themselves.
What it is for
It is used to investigate whether cortisol is being overproduced over the day. It is part of screening for Cushing's syndrome and can be used to monitor known hypercortisolism.
It does not identify the cause of the excess and does not confirm the diagnosis on its own. The result is interpreted together with symptoms, medicines and other tests, such as late-night salivary cortisol or the dexamethasone suppression test.
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
- It is not recommended as a general test for obesity or tiredness without other specific clinical findings
Clinical comment
We have included two collections because cortisol production varies from one day to the next. A single result may not represent the usual pattern, and guidelines recommend repeating the measurement.
The main practical limitation is the collection. If one void is missed, the result may be falsely low; if the time is extended or the collection is incomplete, it no longer represents 24 hours. Reduced kidney function and a very high urine volume also make it less reliable.
Bear in mind that stress, alcohol, some psychiatric conditions, acute illness and certain medicines can raise cortisol without Cushing's syndrome being present. An abnormal result opens an investigation; it does not close it.
Dr. Antonio Mas
What is tested
• 24-hour urine free cortisol (two collections): Measures the free cortisol excreted over two complete 24-hour periods. It reflects daily production and reduces the effect of a one-off variation.
- 24-hour urine free cortisol (two collections)
How to prepare
You must do two complete 24-hour urine collections on different days. For each one, discard the first void and note the time. From then on, keep all your urine, including the first void the next day at the same time. Store the container according to the partner centre's instructions.
If you miss a void, the collection is not valid. Report any corticosteroid you use, including inhalers, creams and injections. Avoid alcohol and intense exercise on the collection days.
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
- Late-night salivary cortisol (two nights)Measures cortisol late at night, when it should be at its lowest, on two different nights. It is one of the first-line tests for investigating excess cortisol, and the sample is collected at home.+€59.00
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
- Late-night salivary cortisol€59.00
- 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
The figures on this page and the two-collection rule come from here. The published sensitivity of urine free cortisol is 91% and its specificity 81.5%, below the 97.5% of salivary cortisol, and the consensus asks for two to three collections because variability between samples from the same person reaches 50%. The kidney warning also comes from here: with a clearance below 60 mL/min or more than five litres of urine a day, the appropriate test is the saliva one.
Endocrine Society · J Clin Endocrinol Metab 93(5):1526-1540
The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline
This is the guideline that sets out the three accepted screening tests, and when it names urine free cortisol it writes the quantity into it: at least two measurements. That bracket is the reason there are two collections here and not one.
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.