Indications
Adrenocorticotropic hormone (ACTH), or corticotropin,
a peptide of 39 amino acids, is first synthesized
as a larger precursor from which ACTH is derived
by proteolytic cleavage. ACTH stimulates
production of glucocorticoids from the adrenal cortex. Release of ACTH depends on diurnal
rhythms with serum levels highest in the early morning.
Secretion of this peptide also increases under stress. It
is easier and less expensive to treat patients having
adrenocortical insufficiency with glucocorticoid replacement
therapy than it is to use ACTH. Therefore,
use of ACTH (Acthar) is restricted to diagnosis; a
shorter 24–amino acid analogue (Cosyntropin) is also
used. Intravenous administration of ACTH should result
in peak plasma levels of glucocorticoids within 30
to 60 minutes if the adrenal gland is functional.
Prolonged administration of ACTH in a repository
form, however, may be necessary to stimulate steroid
production, because ACTH has long-term trophic effects
on adrenal cells in addition to the rapid stimulation
of steroid production. If the cause of steroid deficiency
is at the level of the pituitary gland, ACTH
should eventually stimulate steroid production.
Biological Functions
The main function of Adrenocorticotropic hormone (ACTH) is to regulate the glucocorticoid (steroid) hormone cortisol. Cortisol is released by the adrenal gland. It regulates blood pressure, blood sugar, the immune system, and the response to stress. This test can help find the causes of certain hormone problems
Health Hazard
Adrenocorticotropic Hormone (ACTH;Adrenocorticotropin; corticotropic hormone): (1)Maintenance of adrenal cortex;(2)Promotes secretion of steroids, oxidative phosphorylation in adrenal cortex;(3)Mobilizes and increases oxidation of free fatty acid in adipose tissue;(4)Increases gluconeogenesis in liver; increases cyclic adenosine monophosphate (AMP) in adrenal cortex;Decreases urea formation in liver.
Biochem/physiol Actions
Stimulates synthesis and secretion of glucocorticoids by adrenal cortex.
Producing and consuming organs
The anterior pituitary produces ACTH. It is considered a tropic hormone. Tropic hormones indirectly affect target cells by first stimulating other endocrine glands. Corticotropin-releasing hormone (CRH) is released from the hypothalamus, which stimulates the anterior pituitary to release adrenocorticotropic hormone (ACTH). ACTH then acts on its target organ, the adrenal cortex.
