Cortisol is a steroid hormone produced by the adrenal glands, regulated by ACTH from the pituitary.

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

Clinical uses include:

Diagnosing adrenal insufficiency (Addison’s disease).

Detecting Cushing’s syndrome (excess cortisol production).

Evaluating pituitary or adrenal gland disorders.

Monitoring patients on steroid therapy.

Often performed alongside ACTH stimulation test, dexamethasone suppression test, and evening cortisol levels for comprehensive evaluation.

Analyte: Serum Cortisol (µg/dL).

Normal Range (varies by lab, morning sample): ~5–25 µg/dL (highest in early morning).

Abnormal Findings:

High AM cortisol: Cushing’s syndrome, stress, adrenal hyperplasia, pituitary adenoma.

Low AM cortisol: Addison’s disease, adrenal insufficiency, pituitary dysfunction.

Clinical Use:

Provides a marker of adrenal gland function and stress response.

Helps guide diagnosis and monitoring of endocrine disorders.

Supports critical care and metabolic evaluations.