What Does a Cortisol Test Measure?

The cortisol test measures total cortisol, your primary stress hormone produced by the adrenal glands. Cortisol follows a strong diurnal rhythm — highest in the morning (6-8 AM) and lowest at midnight. It regulates metabolism, immune response, blood pressure, and blood sugar. Both chronically high and low cortisol cause significant health problems.

How the Test Works

The Cortisol test is performed via a standard blood draw at any Quest Diagnostics location. Your sample is sent to a CLIA-certified lab for analysis. Results are typically available within 1-2 business days in your JustLabs account.

Conditions It Helps Diagnose

Who Should Get Tested

Anyone with persistent fatigue, unexplained weight changes, muscle weakness, or symptoms of adrenal dysfunction. Also used to evaluate Cushing's syndrome or Addison's disease.

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Frequently Asked Questions