The work of our body is based on the interaction of all its constituent parts - tissues and organs. However, the main regulators of their functions are biological substances of various structures. These structures include hormones. One such important substance is adrenocorticotropic (or ACTH) hormone.
ACTH (hormone) - what is it
This substance is produced by the pituitary gland - the main endocrine gland responsible for almost all functions. The eosinophilic cells of the anterior pituitary gland are responsible for the production of ACTH.
Translated from Latin, the name of the hormone literally sounds like “related to the adrenal glands”. Transported with blood flow to them, the substance starts the work of these glands, which contributes to the production of substances specific to the adrenal glands. The mechanism of action of the hormones of these glands is aimed at activating almost all protective mechanisms, which is actively manifested during stress.
ACTH itself is a protein molecule. Its structure is quite complex: it has many sections, each of which performs a specific function (attachment to specificreceptors, stabilizes the function of organs, is responsible for the immunogenic effect).
The substance obeys circadian rhythms, i.e. at a certain point in time its concentration is greater than at other times.
Biosynthesis
How is ACTH (hormone) synthesized? What it is is quite difficult to understand, since the molecule combines elements of proteins (amino acids), hydroxyl groups (-OH), and features of biogenic amines (-NH2). Since most of the molecule is a chain of amino acid residues, it is conventionally considered to be a peptide or protein.
The substance is synthesized from the so-called precursor protein. The molecule of proopiomelanocortin acts as the basis for the synthesis of the hormone.
Adrenocorticotropic hormone, as already mentioned, is produced in connection with the circadian rhythm, i.e. time of day. The synthesis itself also depends on the hormone - corticoliberin (the starting hormone of the hypothalamus, which is responsible for triggering the pituitary gland). Corticoliberin is actively produced from 6 to 9 am, and its smallest amount is observed in the blood between 19 and 23 hours. Depending on this, the amount of ACTH in the blood varies.
The role of the hormone
As mentioned, adrenocorticotropic hormone is responsible for the activity of the adrenal glands. Getting into them with the bloodstream, the hormone stimulates the production of glucocorticoids - cortisol, cortisone and adrenocorticosterone. These hormones are actively used by the body to stimulate certain cells and glands. The mechanism of action of hormones is based onbinding them to specific adrenergic receptors located in many tissues, as well as vessels. As mentioned above, these hormones are “stress hormones”, i.e. increase the activity of the body in the presence of danger or as a result of the action of any pathogenic factor.
These hormones have an active anti-inflammatory effect, thanks to which their synthetic derivatives have found application in medicine.
In addition, there is a certain relationship between adrenal hormones and ACTH: the substance increases the concentration of adrenal hormones, and their excess leads to the fact that ACTH (hormone) ceases to be produced. What this phenomenon is and why this happens is still not known, but this paradox itself was called “feedback”.
Clinical significance
ACTH stimulates the activity of the adrenal glands. Without this hormone, these glands would be inactive, leading to various diseases.
However, sometimes it happens that the amount of ACTH in the blood changes, and its determination is necessary. The hormone ACTH, the norm of which in the blood should be from 9 to 46 units (pg / ml), indicates the normal and correct functional activity of the pituitary gland. The amount of the hormone can increase or decrease (usually - to the absolute absence of it in the blood).
An ACTH test is used to determine the level of this peptide.
It is usually carried out when a pathology is suspected. He althy people holding thisstudies not shown.
Judging by the level of the concentration of the hormone in the blood, they conclude on what damage the pathological process is at - at the level of the hypothalamic-pituitary connection or at the level of the connection between the adrenal glands and the pituitary gland.
Determining the level of the hormone in the blood
As already mentioned, to determine the concentration of the hormone, it is necessary to conduct an ACTH test. This procedure allows you to determine whether the patient has this hormone in the blood.
On the eve of the study, it is recommended not to perform heavy physical exertion, and also to refrain from taking alcohol and psychotropic substances. It is not recommended to take spicy and smoked food. Smoking is prohibited 3 hours before the examination.
Blood is usually given on an empty stomach in the morning (only if there are no special instructions from the endocrinologist). In some cases (with suspicion of Itsenko-Cushing's disease), the hormone is examined in the evening.
The patient's venous blood is used for research. It is in it that adrenocorticotropic hormone is determined.
ACTH (its level) after receiving the results is compared with reference values (the hormone normally contains from 9 to 46 pg / ml). Any deviation is usually perceived as a pathology.
Reasons for increased ACTH levels
At what diseases is elevated ACTH? These pathological processes include:
- Addison's disease (bronze disease, primary adrenal insufficiency). The level of ACTH rises due to the fact that the hormones of the adrenal glands are not produced.
- Congenital hyperplasia.
- Itsenko-Cushing's disease (the amount of the hormone is increased due to abnormal concentration of corticoliberins).
- Ectopic ACTH syndrome (a disease associated with the development of pituitary tissue responsible for the production of ACTH in an atypical place).
- Nelson Syndrome.
- Paraneoplastic syndrome (tumor).
- Conditions associated with trauma or surgery.
- Adrenal virilism.
- Taking drugs that directly (directly pituitary hormones) or indirectly (affecting the hypothalamus or suppressing the adrenal glands) regulate the pituitary gland.
- Severe stress or extreme situation.
Decreased hormone levels
Under what conditions is ACTH lowered?
- Secondary adrenal insufficiency. The decrease in ACTH is due to the fact that the adrenal hormones were produced in excessively large quantities, but they could not show their function.
- A tumor of the adrenal glands (Itsenko-Cushing's syndrome). This formation contributes to an increase in the amount of hormone-producing tissue, which as a result leads to an increase in the level of adrenal hormones and inhibition of ACTH synthesis.
- Use of cryptoheptadine. This drug is aimed at suppressing the hunger center located in the hypothalamus. As a result, the synthesis of liberins can also be suppressed.
- Cortisol-producing neoplasms. Somewhat different from the tumor in Itsenko-Cushing's syndrome, but the effect is the same.
- Use of glucocorticoiddrugs in high doses. The natural production of adrenal hormones is artificially reduced, however, due to the large concentrations administered, ACTH ceases to be produced.
Treatment of patients with altered hormone levels
How to cure a patient if he has elevated adrenocorticotropic hormone?
ACTH (a hormone) can be controlled through drug therapy, the use of radiation and surgical methods.
Drug therapy includes the use of cytostatics (used for both increasing and decreasing hormone levels). Most often they are used to confirm the presence of a tumor process. The most widely used "Chloditan", "Mercaptopurine".
Radiotherapy is used when a tumor is located in the brain area. Gamma therapy or proton exposure is applied.
Surgical intervention is prescribed in case of failure of conservative treatment (drugs and radiation). The adrenal gland is usually removed, followed by an intensive course of chemotherapy. Brain tumors are also removed, but the intervention is quite complicated, so it is performed infrequently.
Complications associated with changes in hormone levels
It often happens that an increased or decreased level of ACTH can lead to various complications.
Adrenal crisis is the most common condition that causes an increase in ACTH (hormone). What is itlike this?
Adrenal crisis is characterized by an excessive increase in the level of hormones of the adrenal cortex, which is manifested by tachycardia, increased pressure. Against this background, heart attacks and strokes often develop. In addition, a crisis can lead to exhaustion of the body, which is extremely dangerous and can lead to death.
Decrease in ACTH levels usually leads to the development of adrenal insufficiency, frequent fainting spells or collapse. In addition, sexual function is also partially impaired (because the adrenal glands also produce testosterone and estrogens in a small amount).
It is in order to prevent the development of these disorders that it is recommended to control the level of all hormones in a timely manner.
