• How does this test help determine the specific cause of Cushing's syndrome?

When used with other evaluations, evening ACTH patterns can help distinguish between different types of Cushing's syndrome, such as whether the cause is related to the pituitary gland, adrenal glands, or an external source.

• Is this test used when morning test results are inconclusive?

Yes, this procedure is used to evaluate suspected cases where morning hormone results are borderline or do not provide a clear conclusion.

Medical Laboratories

Evening ACTH Hormone Test

Adrenocorticotropic Hormone (ACTH) Test, Evening

A specialized test to monitor evening stress hormone fluctuations, essential for diagnosing rare conditions like Cushing's syndrome and ensuring the body's natural hormonal rhythm.

Trusted medical contentUpdated: 04-09-2026Views: 34LHL-2997

About this service

The adrenocorticotropic hormone (ACTH) level is measured in blood plasma during the evening or midnight (usually between 10 PM and midnight), when its natural secretion is at its lowest. This is primarily used as part of the dynamic assessment for the diagnosis of Cushing's syndrome (hypercortisolism), in which the normal circadian rhythm is disrupted, and ACTH (and cortisol) levels remain elevated at night.

Conditions and notices

Fasting is not required

Environment and preparation: The test must be performed in a hospital or medical center. The patient needs to be admitted, rest, and lie in a quiet bed for at least one hour before the sample is taken.

Timing: Sample collection between 10 PM and 12 AM, according to the treating physician's protocol.

Absolute rest: Any physical activity or mental exertion should be avoided immediately before and after the examination.

Fasting: Not strictly required, but it is advisable to eat a normal meal at a reasonable time before relaxing.

Medications: Inform your doctor about all medications you are taking. You may be asked to stop medications that affect the axis (such as corticosteroids) well in advance of the examination.

Rapid transport: The sample is extremely sensitive. It must be placed on ice immediately and transported urgently to the laboratory for analysis.

Frequently Asked Questions

Short answers to the FAQs published with this service.

• Why is ACTH measured at night?

It is measured at night because natural levels are typically at their lowest point then. This helps healthcare providers evaluate whether the body's normal daily rhythm of the hormone has been disrupted.

• What is the clinical objective of an evening ACTH test?

The primary objective is to help confirm or exclude Cushing's syndrome by assessing if the normal daily rhythm of ACTH and cortisol has been lost.

• What physical signs might lead a doctor to order this test?

Signs of excess cortisol, such as central weight gain, a rounded face, a fatty hump between the shoulders, or new-onset high blood pressure, may suggest a need for this test.

• Is fasting required for the evening ACTH blood test?

Evening ACTH Hormone Test

About this service

What is included?

Conditions and notices

Frequently Asked Questions

Choose a provider and branch

Let us help you

Didn’t find the service?

Services you might also like

Check Your Stress Hormone

Body Fluid Balance ADH Test

Erythropoietin (EPO) Level Test

ACTH Hormonal Balance Check

Your opinion matters

Was this content helpful?

Have a note?