Adrenocorticotropin (ACTH)

Adrenocorticotropic hormone (adenocorticotropin or corticostimulin) - Peptide hormone secreted by the anterior pituitary gland under the influence of tropical hormones of the hypothalamus. ACTH is synthesized in adenohypophyseal basophilic cells from a precursor called proopimelanocortin.

ACTH controls the development of the adrenal cortex and hormonal activity. By stimulating the adrenal cortex, it activates the synthesis and secretion of glucocorticoids (cortisol and corticosterone). The stimulatory effect of ACTH on adrenal cortex secretion occurs through cyclic AMP 1.

The secondary properties of ACTH are due to the metabolic effects of glucocorticoid hormones, activating the metabolism of carbohydrates, proteins and lipids.

Regulation of ACTH secretion is mediated by indirect involvement of the neuron hypothalamus. The main humoral regulatory factor is the concentration of glucocorticoid hormones in the blood, especially cortisol. Under their influence, ACTH secretion is reduced by a negative feedback mechanism and, consequently, increased in the event of a decrease in circulating glucocorticoids.

When should I take an adrenocorticotropin test?

Adrenocorticotropic hormone - Functional marker of "hypothalamic-pituitary-adrenal cortex" with simultaneous determination of cortisol levels.

• Inadequate fatigue during exercise and chronic fatigue syndrome;
• Differential diagnostics of symptomatic arterial hypertension;
• Differential diagnostics of primary and secondary adrenal insufficiency;
• Suspicion and differential diagnostics of Itzenko-Cushing syndrome with Itzenko-Cushing disease;
• Monitoring of long-term glucocorticoid therapy.
• Ectopic secretion of ACTH (small cell lung carcinoma, pancreatic islet cell carcinoma, carcinoid tumors, thyroid carcinoma), Addison's disease, hypopituitarism, and ACTH-producing pituitary tumors (n.

How to prepare for the test?

A test is required on empty stomach .

The patient should be at rest at the time of sampling (stress causes an increase in plasma ACTH); Plasma ACTH is characterized by diurnal changes in levels. A complete ACTH examination involves taking 2 blood samples: a) between 6 and 10 hours; B) between 21 and 24 hours.

The ACTH evening sample represents 1/2 or 2/3 of the morning value. Daily variation has diagnostic value. Usually, cortisol is determined simultaneously in the blood sample.

Research material

Venous blood

Possible interpretation of the results

The term Cushing's syndrome Refers to all clinical conditions associated with excessive production of cortisol; The determination of ACTH is useful for the differential diagnostics of this syndrome:

• Cushing's disease: Due to excessive pituitary secretion, ACTH levels are moderately elevated or above the normal range (but elevated compared to plasma cortisol levels), with a loss of normal daily variability;
• Ectopic ACTH secretion: ACTH levels are very high;
• Adenoma or adenocarcinoma of the adrenal gland: ACTH levels are too low or undetectable.

The definition of ACTH is also informative in the differential diagnostics of adrenal insufficiency:

• Addison's disease: Due to adrenal destruction, tumor, infectious or autoimmune processes, cortisol production is reduced and ACTH levels are increased;
• Secondary adrenal insufficiency in pituitary insufficiency: ACTH and cortisol levels are low.

Increased levels of ACTH are also found in: Adrenogenital syndrome და Pseudo-Cushing syndrome Time (reversible clinical condition associated with alcohol abuse).