Laboratory Medicine Program

Adrenocorticotropic hormone, plasma (ACTH)
(ACTH)

Clinical Decription:
In response to pain, anxiety and stress via neurotransmitters, the hypothalamus releases corticotrophin releasing hormone (CRH) to control the secretion of adrenocorticotropic hormone (ACTH) in the anterior pituitary gland. ACTH is a 39 amino acid polypeptide that stimulates the adrenal cortex to secrete glucocorticoids like cortisol. The release of CRH is inhibited by an increase of glucocorticoids in the body and increase of cortisol inhibits the secretion of ACTH at the pituitary gland through a negative feedback loop. The determination of ACTH levels is useful in diagnosing disorders of the hypothalamic-pituitary-adrenal system. Increased ACTH levels may be seen in Pituitary Cushing’s disease (secondary hypercortisolism),Addison’s disease (hypocortisolism),Autonomous ACTH producing tumours (ectopic ACTH syndrome). Decreased ACTH levels are found in Adrenal adenoma (primary Cushing’s syndrome and Secondary adrenal insufficiency.Plasma levels of ACTH exhibits significant diurnal variation. The secretion of ACTH increases in frequency during sleep and hours after awakening. Due to the diurnal variation, plasma ACTH samples are typically drawn between 8:00am – 10:00am.

Method: Chemiluminometric technology; Liason

Component Tests Used: n/a

Reference Ranges Used:
< 10.2 pmol/L

Specimen Type: Lavender EDTA
Collected In: EDTA
Volume: 3 mL (minimum: 1 mL)

Shipping: frozen plasma

Special Instructions: Use iced EDTA tube. Immerse tube in ice following collection. Spin in refridgerated centrifuge and aliquot.

Testing Schedule(s): Daily.

Turnaround Time: 7-10 days

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