Adrenocorticotropic Hormone (ACTH), Plasma

What it is:
This test measures the level of adrenocorticotropic hormone (ACTH) in the plasma. ACTH is produced by the pituitary gland and stimulates the adrenal glands to release cortisol, a hormone important for stress response, metabolism, and immune regulation.

Uses

• Diagnose and differentiate causes of adrenal insufficiency (e.g., Addison’s disease vs. secondary adrenal insufficiency)

• Evaluate causes of Cushing’s syndrome (excess cortisol)

• Assess pituitary or adrenal gland disorders

• Monitor effectiveness of treatment for adrenal or pituitary disease

Symptoms That May Lead to the Test

• Unexplained fatigue or weakness

• Weight loss or gain

• Low blood pressure or fainting spells

• Darkening of skin (hyperpigmentation)

• Signs of Cushing’s syndrome (obesity, round face, purple stretch marks, high blood pressure)

• Suspected pituitary or adrenal tumors

Abnormal Results

• High ACTH levels:

  • Addison’s disease (primary adrenal insufficiency)

  • Congenital adrenal hyperplasia

  • Ectopic ACTH-producing tumors (e.g., small-cell lung cancer)

  • Cushing’s disease (pituitary overproduction of ACTH)

• Low ACTH levels:

  • Secondary adrenal insufficiency (pituitary failure)

  • Adrenal tumors producing cortisol (causing feedback suppression)

  • Long-term corticosteroid therapy

Risks

• Minimal, limited to standard blood draw risks (mild pain, bruising, or dizziness).