ACTH (hormone) - what is it? Adrenocorticotropic hormone
The work of our body is based oninteraction of all its constituent parts - tissues and organs. However, the main regulators of their functions are biological substances of various structures. To such structures it is possible to carry hormones. One of these important substances is 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. For the production of ACTH, the eosinophilic cells of the anterior lobe of the pituitary gland correspond.
Translated from Latin, the name of the hormone is literallysounds like "related to the adrenal glands." Transporting with blood flow to them, the substance triggers the work of these glands, which contributes to the development of adrenal-specific substances. The mechanism of action of the hormones of these glands is directed at activating almost all protective mechanisms, which is actively manifested in stress.
ACTH itself is a protein molecule. Its structure is rather complicated: it has a lot of sites, each of which performs a certain function (attachment to specific receptors, stabilizes the function of organs, is responsible for immunogenic action).
The substance is subject to circadian rhythms, ie at a certain point in time its concentration is greater than at other times.
How is ACTH (a hormone) synthesized? What it is is difficult to understand, since in the molecule elements of proteins (amino acids), and hydroxyl groups (-OH), and traits of biogenic amines (-NH2) are combined. 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. As a basis for the synthesis of a hormone, a protomiomelanocortin molecule appears.
Adrenocorticotropic hormone, as already mentioned,is developed 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, responsible for triggering the pituitary gland). Corticoliberin is actively produced from 6 to 9 am, and the 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 is also brewed.
The role of the hormone
As it was said, adrenocorticotropic hormoneresponsible for the activity of the adrenal glands. Getting into them with a current of blood, 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 binding them to specific adrenoreceptors located in many tissues, as well as vessels. As mentioned above, these hormones are "stressful", i.e. increase the activity of the organism in the presence of danger or as a result of the action of any pathogenic factor.
These hormones have an active anti-inflammatory effect, due to which their synthetic derivatives have found application in medicine.
In addition, between the hormones of the adrenal glands and ACTHthere is a certain connection: the substance increases the concentration of adrenal hormones, and their excess leads to the fact that ACTH (a hormone) ceases to be produced. What this is for the phenomenon, and why this happens - is still not known, but the very paradox itself was called "feedback."
ACTH stimulates the activity of the adrenal glands. Without this hormone, these glands would be inactive, which would lead to various diseases.
However, it sometimes happens that the quantityACTH in the blood changes, and its definition is necessary. The hormone ACTH, the norm of which in blood should be equal from 9 to 46 units (pg / ml), speaks about 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).
To determine the level of this peptide, the ACTH test is used.
It is usually performed if there is a suspicion of a pathology. Healthy people are not shown this study.
Judging by the level of concentration of the hormone in the blood,conclude that the pathological process is at what level - at the hypothalamic-pituitary level, or at the level of the connection between the adrenals and the pituitary gland.
Determination of the level of the hormone in the blood
As already mentioned, an ACTH test is needed to determine the concentration of the hormone. This procedure allows you to determine whether there is a hormone present in the patient's blood.
On the eve of the study, it is recommended not to commitheavy physical exertion, and also refrain from taking alcohol and psychotropic substances. It is not recommended to take hot and smoked food. 3 hours before the study, smoking is prohibited.
Blood usually surrenders on an empty stomach in the morning (only if there are no special prescriptions of the endocrinologist). In some cases (with a suspicion of Itenko-Cushing's disease), the hormone is examined in the evening.
The patient's venous blood is used for the study. It is in it that adrenocorticotropic hormone is determined.
ACTH (its level) after the results are compared with reference values (in the norm of the hormone is contained from 9 to 46 pg / ml). Any deviation is usually perceived as a pathology.
The reasons for increasing the level of ACTH
At what diseases is ACTH increased? Such pathological processes include:
- Addison's disease (bronze disease, primary insufficiency of the adrenal cortex). The level of ACTH is increased due to the fact that the hormones of the adrenal glands are not produced.
- Congenital hyperplasia.
- Illness of Itenko-Cushing (the amount of the hormone is increased because of the abnormal concentration of corticoliberins).
- Syndrome of ectopic production of ACTH (a disease associated with the development of pituitary tissue, responsible for the production of ACTH in an atypical location).
- Nelson's syndrome.
- Paraneoplastic syndrome (tumor).
- Conditions related to the transferred trauma or operation.
- Vyrilism of the adrenal glands.
- Taking medications, directly (directly hormonal drugs of the pituitary gland) or indirectly (affecting the hypothalamus or suppressing adrenal glands) regulating the pituitary gland.
- Strong stress or extreme situation.
Decreased hormone levels
At 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 developed in excessively large amounts, but they have not been able to show their function.
- Tumor adrenal gland syndrome (Itenko-Cushing 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 center of hunger, located in the hypothalamus. As a result, the synthesis of liberins can be suppressed.
- Cortisol-producing neoplasms. Somewhat different from the tumor in the Itenko-Cushing syndrome, however, the effect is the same.
- Use of glucocorticoid drugs inlarge doses. Artificially reduces the natural production of adrenal hormones, but due to large introduced concentrations, ACTH ceases to be produced.
Treatment of patients with altered hormone levels
How can a patient be cured if he has an adrenocorticotropic hormone?
ACTH (hormone) can be regulated with the help of drug therapy, the use of radiation and surgical methods.
Medication therapy includesthe use of cytostatics (it is used both with increasing and decreasing the level of the hormone). Most often they are used to confirm the presence of a tumor process. The most widespread are "Chloditan", "Mercaptopurine".
Radiation therapy is used for the location of tumor formation in the brain region. Gamma-therapy or proton therapy is used.
Surgical intervention is prescribed in case ofinefficiency of conservative treatment (drugs and radiation). Usually, the adrenal gland is removed, followed by an intensive chemotherapy course. Tumors of the brain are also removed, but the intervention is rather complicated, so spend it infrequently.
Complications associated with changes in hormone levels
Quite often it happens that an increased or decreased level of ACTH can lead to various complications.
The adrenal crisis is the most common condition, leading to an increase in ACTH (a hormone). What it is?
The adrenal crisis is characterized by excessivean 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, the crisis can lead to the exhaustion of the body, which is extremely dangerous and can lead to death.
Lowering the level of ACTH usually leads to the development ofadrenal insufficiency, frequent attacks of fainting or collapse. In addition, the sexual function is partially violated (as the adrenal glands produce a small amount of testosterone with estrogens).
In order to prevent the development of these disorders, it is recommended that the level of all hormones be monitored in a timely manner.