Cortisol

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Formal name: Cortisol
Related tests: ACTH, aldosterone

At a Glance

Why Get Tested?

To help diagnose Cushing’s syndrome or Addison’s disease or as part of a test for pituitary function or adrenal function (Synacthen test)

When to Get Tested?

If your doctor suspects disease of the adrenal gland or pituitary gland, or rarely a malignant tumour, that could result in the body producing too much cortisol

Sample Required?

A blood sample drawn from a vein in the arm. A 24 hour urine sample or a sample of saliva may be required

Test Preparation Needed?

None. However samples are often taken at particular times: between 8am and 9am and/or close to midnight

The Test Sample

What is being tested?

Cortisol is a steroid hormone, produced by the adrenal gland, in response to the pituitary hormone ACTH. Cortisol is essential for survival. It increases in times of stress and regulates the immune system. Heat, cold, infection, trauma, exercise, obesity and debilitating disease influence cortisol secretion. The hormone is secreted in a daily pattern, rising in the early morning, peaking around 8 a.m., and declining in the evening (diurnal rhythm). This pattern can change in long term night shift workers.

How is the sample collected for testing?

Typically, blood will be drawn from a vein in the arm. Sometimes urine is tested for cortisol; this requires collecting all urine produced during a day (24-hour urine). Cortisol is sometimes now measured in saliva as well. The saliva can be collected at home in special collection tubes.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.