Description

The ACTH test measures the amount of adrenocorticotropic hormone in your blood. ACTH is produced by the pituitary gland in the brain and plays a key role in regulating the adrenal glands, which control cortisol production.

Why the ACTH Test Is Important

ACTH testing helps diagnose and monitor conditions that affect cortisol levels and the function of the pituitary or adrenal glands.

  • High ACTH levels may indicate:
  • Cushing’s Disease – A pituitary tumor causing excess ACTH production.
  • Addison’s Disease – Adrenal gland failure, leading to high ACTH as the pituitary tries to stimulate the adrenals.
  • Ectopic ACTH Syndrome – ACTH production from a tumor outside the pituitary (often in the lungs).
  • Low ACTH levels may indicate:
  • Pituitary Damage – Injury, tumor, or other disorder impairing hormone production.
  • Adrenal Tumor – Producing excess cortisol, which suppresses ACTH.
  • Corticosteroid Medication Use – Long-term use can lower ACTH production.

Fasting: Recommended for the most accurate results.

Best Time to Test: Typically in the morning, when ACTH levels are highest