What is this test?
Cortisol is an adrenal hormone that is involved in stress response, blood pressure, blood sugar and metabolism.
Why might it be ordered?
- For symptoms that warrant an assessment of too low or too high cortisol production.
- To monitor adrenal or pituitary disease and prescribed treatment.
What sample is needed?
A healthcare professional collects a venous blood sample. Depending on the method, the laboratory uses serum or plasma.
How should you prepare?
Cortisol changes throughout the day. Attend at the requested collection time; stress and physical exertion can temporarily raise it. Report all steroid medicines, including creams and inhalers. Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
A single result does not establish the cause of an abnormal cortisol level. Samples collected at different times or stimulation or suppression tests may be needed. Your result is interpreted using the reference interval on the laboratory report and in the context of your symptoms, medical history and other test findings.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.