Cortisol is a steroid hormone produced by the adrenal glands, essential for metabolism, stress response, and immune regulation.

Cortisol levels follow a diurnal rhythm, peaking in the early morning (around 6–8 AM) and declining throughout the day.

Clinical uses include:

Assessing adrenal gland function.

Diagnosing Cushing’s syndrome (excess cortisol).

Diagnosing Addison’s disease/adrenal insufficiency (low cortisol).

Monitoring patients with pituitary or adrenal disorders.

The test is performed using a morning blood sample for accuracy.

Analyte: Cortisol concentration in blood serum (morning sample).

Normal Range (Morning): ~5 – 25 µg/dL (varies slightly by lab).

Low Levels: May indicate adrenal insufficiency, Addison’s disease, pituitary dysfunction, or long-term steroid use.

High Levels: May indicate Cushing’s syndrome, stress, adrenal tumors, or pituitary adenomas.

Clinical Use:

Detects abnormal cortisol production.

Differentiates adrenal vs pituitary causes of hormone imbalance.

Guides treatment and monitoring of endocrine disorders.