Cortisol

This contains the following tests explained;

• • Cortisol 004051 – Establish the diagnosis of adrenocortical insufficiency, Addison’s disease, adrenocortical hypersecretion, and Cushing’s syndrome. Malfunctions of the organs in the hypothalamic-pituitary-adrenal cortex axis will result in an alteration of cortisol levels

Use
This test measures cortisol levels and helps evaluate how well the hypothalamus, pituitary gland, and adrenal glands are functioning. It may be used to help diagnose conditions related to too little or too much cortisol production, including:

• Adrenocortical insufficiency
• Addison’s disease
• Adrenocortical hypersecretion
• Cushing’s syndrome

Because cortisol is regulated through the hypothalamic-pituitary-adrenal (HPA) axis, any dysfunction within this system can affect cortisol levels.

Special Instructions
This test may be affected if the patient is taking high-dose biotin supplements (also known as vitamin B7, vitamin B8, vitamin H, or coenzyme R).

• Patients should be asked whether they are taking any biotin-containing supplements.
• If so, it is recommended to stop biotin at least 72 hours before sample collection to help avoid inaccurate results.

Limitations / Important Considerations

Several factors can influence cortisol results and should be considered when interpreting the test:

• Pregnancy, birth control pills, and estrogen therapy may cause higher cortisol levels
• Certain medications such as prednisolone, methylprednisolone, and prednisone may cause falsely elevated cortisol results
• During metyrapone testing, 11-deoxycortisol levels rise and may affect interpretation
• Patients with 21-hydroxylase deficiency may have elevated 21-deoxycortisol, which can also lead to falsely increased cortisol levels
• Severe stress may temporarily raise cortisol levels

Timing matters:
Cortisol follows a natural daily rhythm (circadian rhythm), with levels typically:

• Highest in the early morning
• Gradually decreasing throughout the day
• Reaching lower levels in the evening

Because of this, the time the sample is collected is essential for proper interpretation.

Possible assay interference:
As with many immunoassays, rare test interference may occur in patients who:

• Have been treated with monoclonal mouse antibodies
• Have high levels of anti-streptavidin antibodies
• Have high levels of anti-ruthenium antibodies

While the assay includes additives designed to reduce these effects, inaccurate results may still rarely occur.

For Cushing syndrome:
When evaluating for Cushing syndrome, a 24-hour urine cortisol test is often preferred because urine cortisol is not affected by the daily fluctuations seen in blood cortisol levels.

Additional Clinical Information

Cortisol (hydrocortisone) is the body’s primary glucocorticoid hormone and plays a major role in maintaining many essential body functions.

It is produced in the zona fasciculata of the adrenal cortex from cholesterol.

In the bloodstream:

• About 90% of cortisol is bound to proteins such as corticosteroid-binding globulin (CBG) and albumin
• Only a small portion circulates freely, and this free cortisol is the biologically active form that can interact with body tissues