Contents
Corticotropin, or adrenocorticotropic hormone, or ACTH (ACTH) is a biologically active substance, a tropic hormone produced by the anterior pituitary gland. The tropic hormone realizes itself through stimulation of the production of hormones by the endocrine glands, or through a tropic (specific) effect on the tissues of the human body, in particular, through the adrenal glands. The term “adrenocorticotropic hormone” originates from the Latin words:
Adrenalis – adrenal;
Cortex – bark;
Tropos – direction.
The adrenal glands are paired glands belonging to the endocrine system. They produce hormones that regulate mineral and electrolyte metabolism, blood pressure, and the functioning of the sex glands.
ACTH is a “young” biologically active substance. In the 20s of the last century, a connection was established between the pituitary, hypothalamus and adrenal glands, where the pituitary gland stimulated the production of hormones by their cortex. The secretion of ACTH is under the control of the hypothalamus, which regulates the function of the pituitary gland.
Neuroendocrinology arose on the basis of the study of the interaction of the hypothalamic-pituitary-adrenal system.
ACTH norm
Reference values may vary within the following ranges:
6-58 pg/ml;
9-52 pg/ml;
Less than 46 pg/ml;
2-11 pmol/l.
Outside of the pregnancy period, the analysis is done on the 6-7th day of the cycle; in pregnant women, the doctor determines the duration of this test.
Adrenocorticotropin and the synthesis of adrenal hormones
ACTH is a 39 amino acid peptide. The production of corticotropin is controlled by the hypothalamus, after its formation it begins to control the production of glucocorticosteroids, including the stress hormone cortisol. In accordance with the feedback mechanism, cortisol also affects the secretion of adrenocorticotropin.
In accordance with the feedback mechanism, the hormones of the adrenal cortex control the release of corticotropic hormone into the blood. ACTH directly affects the accumulation of cholesterol and vitamins C, B in the body5, stimulates the synthesis of proteins, amino acids, thereby provoking hypertrophy of the endocrine glands. The larger the gland, the higher the level of hormones secreted by it in the blood.
Against the background of an increased release of corticoids into the blood, ACTH during serious injuries, high-intensity stress, after surgical interventions causes the formation of a cortical adenoma.
Analysis for ACTH
Indications for a laboratory study of corticotropic hormone – differential diagnosis of impaired functioning of the adrenal glands and the following conditions:
Syndrome Itenko-Cushing.
Primary or secondary adrenal insufficiency.
Secondary arterial hypertension.
Long-term glucocorticoid therapy.
Weakness, dysfunction.
Pathologies requiring differential diagnosis.
ectopic tumors.
Addison’s disease.
Nelson’s syndrome, accompanied by a pituitary tumor and adrenal insufficiency.
Adrenoleukodystrophy, affecting the adrenal glands, provoking the accumulation of fatty acids.
The analysis is carried out on an empty stomach early in the morning, sports and intense exercise are excluded the day before. In women, an analysis for ACTH is performed on the 6-7th day from the onset of menstruation. When diagnosing Cushing’s disease, additional blood is taken in the evening.
The analysis of the material is carried out by enzyme immunoassay (ELISA), the results can be announced in 1-2 weeks. This is possible by freezing the serum prior to collecting samples for a 96-well microplate.
An understandable analysis of ACTH
If the content of ACTH in the blood exceeds the norm by one and a half or more times, therefore, there is a pathology. Be sure to take into account the time period of blood sampling, since ACTH is characterized by diurnal fluctuations.
The maximum concentration of ACTH in the blood is 6-8 hours in the morning;
The minimum level is 21-22 hours.
Other factors affecting the secretion of corticotropin:
Change of climatic and time zone, valid for 7-10 days after the change.
Physical stress, psycho-emotional overload.
Infection, the presence of an inflammatory process that activates the endocrine system with cytokines.
In the presence of these factors, cortisol takes over the control of the body’s adaptation, which delays the production of ACTH.
What does the change in ACTH say?
A slight increase in the level of corticoids during pregnancy is physiologically justified; in other cases, a significant increase in ACTH values is a sign of pathology.
Diseases that provoke an increased level of adrenocorticotropin:
Genetically determined adrenal insufficiency;
Itsenko-Cushing’s disease, the symptoms of which are provoked by excessive production of actg;
Hypothalamo-pituitary Cushing’s syndrome, which is expressed in an increase in the concentration of cortisol against the background of a slight increase in the level of actg;
Cushing’s syndrome with increased production of actg by tumors (for example, lung cancer);
Addison’s disease, with excessive synthesis of actg against the background of primary adrenal insufficiency;
Treatment of pathologies of the endocrine system by removing both adrenal glands;
The premature development of male sexual characteristics due to adrenal virilism;
Ectopic crg syndrome;
Hypoglycemia caused by insulin injections;
Condition after operations and injuries;
Intravenous and intramuscular administration of actg or metopyralone for the diagnosis of adrenal function.
Reasons for a decrease in ACTH levels:
Loss of up to 90% of the functionality of the adrenal glands, which led to insufficiency of production of ACTH;
Pathologies of the hypothalamus, leading to a secondary insufficiency in the production of ACTH;
The presence of tumors that produce cortisol (carcinoma of the adrenal cortex, cortical adenoma);
Use of cryptoheptadine to minimize tumor production of corticotropin;
Introduction of glucocorticoid hormones.
Functional tests are used to differentiate the above states. So, for example, in Cushing’s disease, the introduction of a large amount of dexamethasone inhibits the production of ACTH and cortisol (stress hormone), and such a reaction is not observed in adenoma and cancer of the adrenal glands.