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ACTH (Adrenocorticotropic Hormone)

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Adrenocorticotropic hormone (ACTH) is a hormone produced by the anterior pituitary gland. Its release is triggered by corticotropin-releasing hormone (CRH), secreted by the hypothalamus, and it stimulates the biosynthesis and secretion of cortisol in the adrenal cortex. Additionally, ACTH plays a minor role in androgen synthesis but has little effect on aldosterone production at physiological levels. ACTH levels are significantly influenced by stress, sleep, physical activity, and pregnancy.

Cushing’s Syndrome and Disease

  • Cushing’s Syndrome is characterized by the presence of adrenal tumors (corticosteromas or adrenal cancer), which cause excessive cortisol production. As a result, ACTH secretion is significantly reduced due to negative feedback.

  • Cushing’s Disease occurs due to pituitary adenoma or hyperplasia, leading to excessive ACTH production, adrenal cortex hyperplasia, and increased blood cortisol levels. Urinary free cortisol and 17-ketosteroid excretion are also elevated.

  • Ectopic ACTH Syndrome refers to abnormal ACTH secretion by non-pituitary tumors (commonly bronchial carcinoma or thymoma, and sometimes medullary thyroid cancer, ovarian, breast, stomach, or colon cancer). This results in elevated ACTH levels, leading to adrenal cortex hyperplasia and excessive cortisol secretion.

  • Avoid fatty foods for 24 hours before the test.
  • Do not eat for 12 hours before the test.
  • Avoid taking medications for 24 hours before the test (consult your doctor).
  • Avoid physical and emotional stress for 24 hours before the test.
  • Do not smoke for 3 hours before the test.
  • Evaluation of adrenal cortex function (along with cortisol measurement).
  • Differential diagnosis of Cushing’s disease and various forms of Cushing’s syndrome (in combination with cortisol testing).
  • Monitoring the effectiveness of tumor treatment, including surgical removal.
  • Testing with corticotropin-releasing hormone (CRH).
  • Suspicion of an ACTH-producing tumor.
  • Evaluation of abnormal cortisol levels (high or low).
  • Post-transsphenoidal resection of a corticotropinoma (ACTH-secreting pituitary tumor).

Causes of Elevated ACTH Levels:

  • Addison’s disease (primary adrenal insufficiency)
  • Congenital adrenal hyperplasia
  • Cushing’s disease (pituitary adenoma overproducing ACTH)
  • Ectopic ACTH-producing tumors
  • Nelson’s syndrome
  • Paraneoplastic syndrome
  • Post-traumatic and post-surgical conditions
  • Adrenal virilism
  • Medications: ACTH, amphetamines, calcium gluconate, metyrapone, insulin, vasopressin, ethanol, estrogens, corticosteroids, lithium, spironolactone
  • Stress

Causes of Decreased ACTH Levels:

  • Secondary adrenal insufficiency
  • Adrenal carcinoma or adrenal adenoma (Cushing’s syndrome)
  • Glucocorticoid therapy
  • Use of cyproheptadine
  • Cortisol-producing tumor