ACTH, aka adrenocorticotropic hormone or corticotropin, is a peptide hormone produced by the corticotropic cells of the anterior pituitary gland. What is the role of ACTH? What is its correct level? What are the risks of excess or deficiency of corticotropin?
Corticotropin( ACTH ,Adrenocorticotropic hormone ) consists of 39 amino acids, has a mass molecular weight 4500 and belongs to the group of peptides that are formed from the precursor, the so-called proopiomelanocortin (POMC), in the process of post-translational proteolysis together with β-endorphin, lipotropin (LSH) and melanotropin (MSH). It is a trophic hormone for the band and reticular layers of the adrenal glands.
ACTH secretion is regulated by the hypothalamic corticotropin releasing hormone (CRH) and by adrenal cortisol derived negative feedback. This is synonymous with the fact that cortisol deficiency stimulates, and excess inhibits the secretion of CRH and ACTH.
In addition, an increase in ACTH secretion from the pituitary gland is observed during stress caused by emotional factors, mental factors, trauma, infections, severe diseases, surgery or hypoglycemia.
It is worth knowing that the adrenocorticotropic hormone is secreted in pulses, in the so-called circadian rhythm. This means that its highest concentration is present in the morning (just before waking up), and then decreases as the day progresses, reaching the lowest concentration in the evening.
ACTH regulates the function of the adrenal cortex - affects the secretion of glucocorticosteroids, adrenal androgens and, to a lesser extent, the secretion of mineralocorticosteroids.
ACTH secretion increases in:
- primary adrenal insufficiency (Addison's disease)
- Cushing's disease (adrenocorticotropic adenoma which autonomously releases excessive amounts of ACTH)
- Nelson's syndrome (adrenocorticotropic adenoma, which produces excessive amounts of ACTH after bilateral adrenalectomy)
The decrease in ACTH secretion is observed:
- in patients with cortisol-producing adrenal tumors (Cushing's syndrome)
- in the course of secondary (pituitary) adrenal insufficiency
Finally, it is worth mentioning that chronic ACTH overstimulation of the adrenal cortex leads to its hypertrophy and hyperplasia, while ACTH deficiency causes adrenal atrophy.