The work of our body is based on the interaction of all its components - tissues and organs. However, the main regulators of their functions are biological substances of various structures. These structures include hormones. One of these important substances is the adrenocorticotropic (or ACTH) hormone.
ACTH (hormone) - what is it
This substance is produced by the pituitary gland - the main endocrine gland, responsible for the performance of almost all functions. 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." Being transported with a blood stream to them, the substance starts the work of these glands, which contributes to the development of substances specific to the adrenal glands. The mechanism of action of the hormones of these glands is aimed at the activation of almost all protective mechanisms, which is actively manifested during stress.
ACTH itself is a protein molecule. Its structure is quite complex: there are many sites on it, each of which performs a specific function (attachment to specific receptors, stabilizes the function of organs, and is responsible for the immunogenic effect).
The substance is subject to 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 protein combines elements of proteins (amino acids), and 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 proopiomelanocortin molecule 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 starting the pituitary gland). Corticoliberin is actively produced from 6 to 9 in the morning, and its smallest amount is observed in the blood in the interval between 19 and 23 hours. Depending on this, the amount of ACTH in the blood varies.
Hormone role
As stated, adrenocorticotropic hormone is responsible for adrenal gland activity. Getting into them with a blood stream, 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 on their binding to specific adrenergic receptors located in many tissues, as well as vessels. As mentioned above, these hormones are “stressful”, 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, so their synthetic derivatives are used in medicine.
In addition, there is a certain connection between the hormones of the adrenal glands and ACTH: a 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, however, this paradox itself was called “feedback”.
Clinical significance
ACTH stimulates adrenal gland activity. Without this hormone, these glands would be inactive, which would lead 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 equal to 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 its absolute absence in the blood).
To determine the level of this peptide, an ACTH test is used.
It is usually carried out with suspected pathology. This study is not indicated for healthy people.
Judging by the level of hormone concentration in the blood, they conclude on what damage the pathological process is at the level of the hypothalamic-pituitary connection or at the level of communication between the adrenal glands and the pituitary gland.
Determination of the level of 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 this hormone is in the patient's blood.
On the eve of the study, it is recommended not to commit heavy physical exertion, as well as to refrain from taking alcohol and psychotropic substances. It is not recommended to take spicy and smoked food. 3 hours before the study, smoking is prohibited.
Blood is usually given on an empty stomach in the morning (only if there is no special prescription from an endocrinologist). In some cases (with suspected Itenko-Cushing's disease), the hormone is tested in the evening.
For research, venous blood of the patient is used. It is in it that the adrenocorticotropic hormone is determined.
ACTH (its level) after obtaining the results is compared with reference values (normally the hormone contains from 9 to 46 pg / ml). Any deviation is usually perceived as a pathology.
Reasons for increasing ACTH
What diseases have increased ACTH? These pathological processes include:
- Addison's disease (bronze disease, primary adrenal insufficiency). The level of ACTH increases due to the fact that hormones of the adrenal glands are not produced.
- Congenital hyperplasia.
- Itsenko-Cushing's disease (the amount of the hormone is increased due to the pathological concentration of corticoliberins).
- The syndrome of ectopic ACTH production (a disease associated with the development of pituitary tissue responsible for the production of ACTH in an atypical place).
- Nelson's syndrome.
- Paraneoplastic syndrome (tumor).
- Conditions associated with an injury or surgery.
- Adrenal virilism.
- Taking drugs that directly (directly hormonal drugs of the pituitary gland) or indirectly (affecting the hypothalamus or suppressing the adrenal glands) regulate the work of the pituitary gland.
- Severe stress or extreme situation.
Hormone lowering
Under what conditions is ACTH reduced?
- Secondary adrenal insufficiency. The decrease in ACTH is due to the fact that the hormones of the adrenal glands have been produced in an excessively large amount, but have failed to show their function.
- Adrenal tumor (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.
- The use of cryptoheptadine. This drug is aimed at suppressing the center of hunger located in the hypothalamus. As a result of this, the synthesis of liberins can be suppressed.
- Cortisol-producing neoplasms. Somewhat different from a tumor in Itsenko-Cushing's syndrome, however, the effect is the same.
- The use of glucocorticoid drugs in large doses. The natural production of adrenal hormones is artificially reduced, however, due to the large injected concentrations, ACTH ceases to be produced.
Treatment of patients with altered hormone levels
How to cure a patient if he has an increased adrenocorticotropic hormone?
ACTH (hormone) can be regulated with the help of drug therapy, the use of radiation and surgical methods.
Drug therapy includes the use of cytostatics (used both with increasing and decreasing hormone levels). Most often they are used to confirm the presence of a tumor process. The most widely used are “Hloditan”, “Mercaptopurin”.
Radiation therapy is used to locate a tumor in the area of the brain. Gamma therapy or proton exposure is used.
Surgical intervention is prescribed in case of failure of conservative treatment (with drugs and radiation). The adrenal gland is usually removed, followed by an intensive course of chemotherapy. Tumors of the brain are also removed, but the intervention is quite complicated, therefore, it is performed infrequently.
Hormone Complications
Quite often it happens that an increased or decreased level of ACTH can lead to various complications.
Adrenal crisis is the most common condition that leads to an increase in ACTH (hormone). What it is?
The 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 depletion of the body, which is extremely dangerous and can lead to death.
Lowering the level of ACTH usually leads to the development of adrenal insufficiency, frequent bouts of fainting or collapse. In addition, sexual function is partially impaired (because the adrenal glands also produce testosterone with estrogens in a small amount).
It is in order to prevent the development of these disorders, it is recommended to monitor the level of all hormones in a timely manner.