Overview

• Measures the amount of unbound (free) cortisol excreted in urine collected over 24 hours.

• Reflects overall cortisol production by the adrenal glands.

• Used to evaluate disorders of the adrenal cortex, especially Cushing’s syndrome and Addison’s disease.

Risk Assessment / Purpose

• High cortisol detection → screening for Cushing’s syndrome, adrenal tumors, ectopic ACTH production.

• Low cortisol detection → suggests adrenal insufficiency (Addison’s disease) or pituitary dysfunction.

• Helps assess chronic stress, iatrogenic steroid excess, and evaluation of treatment response in adrenal disorders.

Normal Range

• 24-hour urine free cortisol:
  20–90 µg/24 hours
  (May vary slightly between laboratories.)

Interpretation

• ↑ Increased levels:

  • Cushing’s syndrome (pituitary or adrenal cause)

  • Ectopic ACTH secretion

  • Severe stress, depression

  • Obesity

  • Pregnancy

  • Alcoholism

  • Hyperthyroidism

• ↓ Decreased levels:

  • Addison’s disease

  • Secondary adrenal insufficiency

  • Hypopituitarism

  • Long-term steroid therapy (suppression of adrenal function)

Note: Must ensure complete 24-hour urine collection for accurate interpretation.

Sample Type

• 24-hour urine sample

• Collected in a special container, usually with a preservative (e.g., boric acid).

• Requires proper storage, usually kept cool or refrigerated during collection.