Cortisol Test

Cortisol is your body’s primary stress hormone, and measuring it offers insight into fatigue, stress-related symptoms and how well your adrenal glands are functioning.

About the Cortisol Test

This test measures cortisol, a hormone produced by the adrenal glands that helps regulate metabolism, blood pressure and the body’s response to stress. Levels that are too high or too low can cause a range of symptoms and may indicate an adrenal or pituitary condition. Because cortisol follows a daily rhythm, the timing of the sample is important for accurate interpretation.

Preparation and turnaround

Cortisol is usually measured in the morning, when it naturally peaks, so an early appointment is recommended; fasting is not generally required. Results are typically available within one to two working days. Because cortisol varies through the day and with stress, results are best reviewed by a doctor.

Frequently asked questions

Why does the timing of the test matter?

Cortisol follows a daily rhythm, peaking in the morning and falling through the day, so a morning sample is usually preferred for consistency.

What can abnormal cortisol indicate?

Levels that are too high or too low can relate to adrenal or pituitary conditions, and are interpreted alongside your symptoms.

Is fasting required?

Fasting is not generally required, but a morning sample is recommended.