ACTH: what is this hormone and what is it responsible for?
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 the 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" takes its origin from the Latin words:
- Adrenalis - adrenal;
- Cortex - bark;
- Tropos - direction.
The adrenal glands are paired glands that belong to the endocrine system. They produce hormones that regulate mineral and electrolyte metabolism, blood pressure, and the functioning of the gonads.
ACTH is a "young" biologically active substance. In the 20s of the last century, a connection was established between the pituitary gland, hypothalamus and adrenal glands, where the pituitary gland stimulated the production of hormones by the cortex. The secretion of ACTH is under the control of the hypothalamus, which regulates the function of the pituitary gland.
Neuroendocrinology arose from the study of the interaction of the hypothalamic-pituitary-adrenal system.
- Norm ACTH
- Adrenocorticotropin and adrenal hormone synthesis
- Analysis for ACTH
- We analyze the analysis for ACTH
- What does ACTH change say?
The norm of adrenocorticotropic hormone (ACTH) content in human blood is 10.0-70.0 ng / l. It does not depend on gender and age, although during menstruation and pregnancy, women may have slight deviations from the norm.
The reference values can fluctuate in the following ranges:
- 6-58 pg / ml;
- 9-52 pg / ml;
- Less than 46 pg / ml;
- 2-11 pmol / l.
Outside the period of pregnancy, the analysis is done on the 6-7th day of the cycle; in pregnant women, the duration of this test is determined by the doctor.
Adrenocorticotropin and adrenal hormone synthesis
ACTH is a peptide of 39 amino acid residues. 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. According to the feedback mechanism, cortisol also affects the secretion of adrenocorticotropin.
By influencing the production of glucocorticosteroids, ACTH simultaneously stimulates the production of sex hormones and mineralocorticoids
In accordance with the feedback mechanism, 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 5 in the body, 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 in the blood.
Against the background of an increased release of corticoids into the blood, ACTH in case of serious injuries, high-intensity stress, after surgery, causes the formation of a cortical adenoma.
Analysis for ACTH
Indications for a laboratory study of corticotropic hormone are differential diagnosis of adrenal dysfunction and the following conditions:
- Itsenko-Cushing's syndrome.
- Primary or secondary adrenal insufficiency.
- Arterial hypertension of a secondary nature.
- Long-term current glucocorticoid therapy.
- Weakness, impaired performance.
- Pathologies requiring differential diagnosis.
- Ectopic tumors.
- Addison's disease.
- Nelson's syndrome, accompanied by a pituitary tumor and adrenal insufficiency.
- Adrenoleukodystrophy, which affects 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 loads are excluded the day before. In women, an ACTH test is performed 6-7 days after the onset of menstruation. When Cushing's disease is diagnosed, additional blood is taken in the evening.
The analysis of the material is carried out by the enzyme immunoassay (ELISA), the results can be announced after 1-2 weeks. This is possible by freezing the serum prior to sample collection for the 96-well microplate.
We analyze the analysis for 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. The time period of blood sampling is necessarily taken into account, since ACTH is characterized by daily fluctuations.
- The maximum concentration of ACTH in the blood is 6-8 am;
- The minimum level is 21-22 hours.
When examining the level of ACTH in dynamics, blood samples are taken at the same time.
Other factors affecting corticotropin secretion:
- Change of climatic and time zone, valid for 7-10 days after the change.
- Physical overstrain, 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 control of the body's adaptation, which delays the production of ACTH.
What does ACTH change 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 provoking an increased level of adrenocorticotropin:
- Genetically determined adrenal insufficiency;
- Itsenko-cushing's disease, the symptoms of which are provoked by excessive production of aktg;
- Hypothalamic-pituitary syndrome of itsenko-cushing, expressed in an increase in the concentration of cortisol against the background of a slight increase in the level of AKT;
- Cushing's syndrome with increased production of ACT by tumors (eg, lung cancer);
- Addison's disease, with excessive synthesis of aktg against the background of primary adrenal insufficiency;
- Treatment of pathologies of the endocrine system by removing both adrenal glands;
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 aktg or metopyralone to diagnose the functionality of the adrenal glands.
Reasons for a decrease in ACTH levels:
- Loss of up to 90% of the functionality of the adrenal glands, leading to a deficiency in the production of ACTH;
- Hypothalamic pathologies leading to secondary ACTH production failure;
- The presence of tumors that produce cortisol (adrenal cortex carcinoma, cortical adenoma);
- Use of cryptoheptadine to minimize tumor production of corticotropin;
- Administration of glucocorticoid hormones.
Functional tests are used to differentiate the above states. For example, in Cushing's disease, the administration of a large amount of dexamethasone inhibits the production of ACTH and cortisol (stress hormone), while in adenoma and adrenal cancer, such a reaction is not observed.
Author of the article: Alekseeva Maria Yurievna | Therapist
Education: From 2010 to 2016 Practitioner of the therapeutic hospital of the central medical-sanitary unit No. 21, city of elektrostal. Since 2016 she has been working in the diagnostic center No. 3.