Adrenocorticotropic Hormone (ACTH)

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Latest Edit: Hector 2014-3-21 (EDT)

See Also Lab Tests

This test is used to help diagnose adrenal and pituitary conditions such as Cushing's syndrome, Cushing's disease, Addison's disease, adrenal tumors, and pituitary tumors. Symptoms associated with excess or deficient cortisol production are usually the basis for this test being conducted.[1], [2]


Contents

Discussion

  • The ACTH test measures the amount of adrenocorticotropic hormone, or ACTH in the blood.
  • ACTH is a hormone produced by the pituitary gland that stimulates the production of cortisol, which is a steroid hormone important for regulating glucose, protein, and lipid metabolism, suppressing the immune system's response, and maintaining blood pressure.
  • ACTH levels are generally seen to increase when cortisol is low and fall when cortisol is high.

Patient Preparation

  • Overnight fasting may be required before testing.
  • Blood is typically drawn in the morning, about 8 a.m.
  • Factors which can cause increased levels:
  • Stress
  • Drugs: Amphetamines, insulin, levodopa, metoclopramide, and RU 486.
  • Factors which can cause decreased levels:
  • Drugs: Dexamethasone, drugs that act like cortisol including prednisone, hydrocortisone, prednisolone, methylprednisolone, and megestrol acetate.

Clinical Implications

When assessing the relevance of ACTH it is also important to look at the levels of cortisol.

High levels indicate:

Low levels indicate:

  • Adrenal tumor
  • Hypopituitarism
  • Steroid medication

Associated Tests

  • Cortisol, Cortrosyn (ACTH) stimulation test, Dexamethasone suppression test

References

  1. Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.
  2. Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain.
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