Quick Facts
- Sample: Blood
- Fasting: No fasting is required. Schedule collection between 3–6 PM. Avoid prednisone/prednisolone for 72 hours and biotin supplements for 72 hours before testing. Report contraceptive use, hormone therapy, or pregnancy.
- Turnaround: 1-2 business days. May take longer based on weather, holiday, or lab delays.
What This Test Measures
The Cortisol Blood Test, PM measures the level of cortisol in your blood during the afternoon or evening. Cortisol is a hormone produced by your adrenal glands that plays a role in metabolism, immune response, and your body's stress response. This test captures your cortisol level at a specific point later in the day, when cortisol naturally sits lower than it does in the morning.
This test reflects a single afternoon or evening measurement of circulating cortisol. It does not track cortisol at other times of day and does not measure any other hormone or adrenal marker.
Benefits
- Checks your cortisol level during the afternoon or evening window.
- Supports evaluation of adrenal gland function.
- Helps your provider assess symptoms tied to cortisol imbalance.
- Can help monitor how treatment affects cortisol over time.
- Adds a later-day data point to your overall hormone picture.
Who Is This Test For?
- People with suspected adrenal gland concerns needing afternoon cortisol data.
- People experiencing chronic fatigue they want evaluated.
- People with mood changes who want cortisol checked.
- People with sleep disturbances they want to explore.
- People monitoring treatment that may affect cortisol levels.
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. What is the purpose of this hormone test?
The Cortisol Blood Test, PM measures your circulating cortisol level in the afternoon or evening. Cortisol is produced by the adrenal glands and helps regulate metabolism, immune response, and stress. This measurement may help a healthcare provider evaluate adrenal gland function as part of a broader clinical picture. It is not a standalone diagnostic tool.
2. Who would benefit from this test?
This test may benefit people who want their afternoon or evening cortisol level checked, including those with suspected adrenal gland concerns, chronic fatigue, mood changes, sleep disturbances, or those monitoring treatment that may affect cortisol. A healthcare provider can help determine if this test is appropriate for your situation.
3. When should I order this test?
You might consider this test if you and your provider want to evaluate afternoon or evening cortisol levels, whether to help investigate symptoms, assess adrenal gland function, or monitor treatment over time. This test does not diagnose a condition on its own and works best alongside a full clinical evaluation.
4. How does this test differ from other hormone tests?
This test measures cortisol specifically in the afternoon or evening, capturing your cortisol level at the point in the day when it naturally sits lower than in the morning. It reflects circulating cortisol at that time only, not a full daily pattern and not any other hormone.
5. Do I need to fast before this test?
No fasting is required. Blood is drawn in the late afternoon. You should stop biotin consumption at least 72 hours prior to collection.
6. How quickly will I get results?
Results are typically available in 1 to 2 days. This may take longer based on weather, holiday, or lab delays.
7. How do I interpret the results?
The meaning of your cortisol result depends on your individual symptoms, medical history, the time of collection, and other factors your provider considers. Afternoon or evening cortisol results are often interpreted alongside other clinical information rather than on their own. An abnormal result does not automatically confirm a hormonal condition, and a normal result does not rule one out. Discuss your results with a qualified healthcare provider for proper interpretation.
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.
8. What should I do if my results are abnormal?
If your results fall outside the expected range, review them with a qualified healthcare provider. They can help determine whether additional evaluation or testing is appropriate based on your overall health and symptoms. Do not attempt to interpret or act on abnormal results without professional guidance.
9. How often should I get tested?
Testing frequency should be determined by your healthcare provider based on your individual health needs and reason for testing. Follow their guidance for any repeat testing.
Pre-test preparation
No fasting is required for PM cortisol testing. Schedule your blood draw specifically between 3:00-6:00 PM to capture the natural circadian decline in cortisol levels. Avoid prednisone or prednisolone therapy for at least 72 hours prior to testing due to cross-reactivity.
Discontinue biotin supplements at least 72 hours before collection. Women should note if taking contraceptives, hormone replacement therapy, or if pregnant, as these can elevate cortisol concentrations.
