Quick Facts
- Sample: Urine (Discard first 8 a.m.urine)
- Fasting: No fasting required, but a 24-hour urine collection is required
- Turnaround: 4-6 days (may take longer due to weather, holidays, or lab delays; current delays may add 3 business days)
What This Test Measures
This test measures free cortisol in a urine specimen collected over a full 24-hour period. Cortisol is a hormone produced by the adrenal glands that plays a role in immune function, nervous system activity, metabolism, and the body's response to stress.
Because this is a 24-hour urine collection rather than a single random or timed sample, the result reflects the total free cortisol excreted over an entire day rather than a single point-in-time measurement. Results are reported for free cortisol in urine, distinct from serum or blood cortisol testing, which measure cortisol differently and are not interchangeable with this urine-based result.
Benefits
- Measures free cortisol excreted in urine over 24 hours
- Offers a broader collection window than a single blood draw
- Supports evaluation of adrenal gland hormone activity
- Provides objective, lab-based cortisol data for your provider
- Can be repeated over time to track free cortisol levels
Who Is This Test For?
- Individuals experiencing symptoms associated with excess cortisol
- Individuals experiencing symptoms associated with insufficient cortisol
- Those whose provider is considering screening for adrenal-related conditions
- Individuals wanting objective lab data on 24-hour free cortisol levels
- Those who can reliably complete a full 24-hour urine collection
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. Do I need to fast before this test?
No fasting is required for this test. However, you must receive a specimen container from the lab before beginning your collection, and you must follow the full 24-hour urine collection protocol described in the preparation instructions.
2. How quickly will I get results?
Results are typically available in 4-6 days. This timeframe may take longer depending on weather, holidays, or lab delays. At this time, the lab is experiencing delays that could add 3 business days to the normal turnaround time.
3. Can timing or collection conditions affect this test?
Yes. This test requires a precise 24-hour collection process. Begin by urinating at 8am and discarding that first specimen, then collect all urine produced over the next 24 hours, ending with a final collection at 8am the following day. The specimen must be kept refrigerated or in a cool place between voidings, and the container must be labeled with your full name and the exact date and time the collection started and finished. Incomplete or improperly stored collections may affect your results.
4. Can this test identify the cause of fatigue by itself?
No. Fatigue can result from many different factors, and this test measures only one specific marker, free cortisol excreted in urine over 24 hours. A single result from this test does not establish the cause of fatigue on its own, and a normal result does not rule out other potential causes. Your healthcare provider can help interpret this result alongside your broader clinical picture.
5. How do I interpret the results?
Interpreting your 24-hour urinary free cortisol result depends on factors such as your symptoms, medical history, medications, and how accurately the full 24-hour collection was completed. Because this result reflects total free cortisol over an entire day, it should not be read the same way as a single random or timed blood cortisol value. A high or low result does not by itself confirm a specific adrenal condition, and a normal result does not rule one out. Your healthcare provider is best positioned to interpret this result in context.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
6. What should I do if my results are abnormal?
If your results fall outside the expected range, review them with a qualified healthcare provider. An abnormal result does not by itself indicate what treatment, if any, may be needed. Your provider can help determine whether any additional evaluation is appropriate based on your individual health history.
Pre test preparation
You must receive a specimen container from the lab prior to collection. No fasting is required. Start by urinating at 8am and discard the specimen. Then, collect all urine for 24 hours, ending with final collection at 8am the following day. Keep the collected specimen refrigerated between all voidings or in a cool place, and return the container to the lab after 24 hours. The container must be labeled with full name, date and time collection started, and date and time collection finished.
