Androgens

The main representatives of androgens in the female body are testosterone, androstenedione and DHEAS.Androgens stimulate the growth of hair on the pubic and axilla, increase libido and affect the size of the clitoris and large labia. Androgens modulate the production of gonadotropins in the anterior pituitary gland.

In the body of men, the main representatives of androgens are testosterone and dihydrotestosterone( DHT).Most of the testosterone in the blood serum is associated with SSH( approximately 60%).The proportion of free testosterone is 1-3%, and the proportion of testosterone associated with albumin is approximately 40%.In the target organs( prostate, seminal vesicles and skin), only free testosterone and testosterone, bound to albumin, can penetrate. After reaching the target organ and penetrating the cells, testosterone is converted to DHT by means of 5a-reductase( the main amount is formed in the prostate gland), and only after this DHT has its biological effect. In other target organs, such as muscles and kidneys, the effect of androgens is carried out directly. Gy-perandrogenemia in women leads to virilization and impaired fertility. This determines the importance of determining androgens in the diagnosis of female infertility.

Testosterone in the blood serum

Testosterone is an androgenic hormone responsible for secondary sexual characteristics in men. The most important source of testosterone is Lei-diga cells of the testes. Testosterone supports spermatogenesis, stimulates the growth and function of additional sexual glands, as well as the development of the penis and scrotum. The hormone has an anabolic effect, mainly in relation to bones and muscles. Due to direct effects on the bone marrow, and also by activating the synthesis of erythro-poetin in the kidneys, testosterone stimulates erythropoiesis. A hormone is also needed to maintain libido and potency. The synthesis of testosterone is controlled by the LH of the anterior lobe of the pituitary gland. In men, this is the main androgen, which determines the achievement of sexual maturity. The concentration of the hormone in the blood increases after exercise. Reference values ​​of serum testosterone concentration are given in Table.

In adults of healthy men, peak testosterone concentrations occur in the morning and decrease by at least 25% in the evening. After 50 years, there is a progressive decrease in testosterone in the blood.

Serum testosterone concentration increases with idiopathic premature puberty and hyperplasia of the adrenal cortex in boys, adrenal cortex tumors, extragonadal tumors in men, with trophoblast diseases in pregnant women, arreno-blastomas.

Reduction of testosterone concentration in the blood is noted with Down's syndrome, delayed puberty. The main diseases and conditions in men and women in which the concentration of testosterone in the blood can vary is shown in Table.

Table Diseases and conditions in which the testosterone concentration in the blood serum changes

End of Table.

The use of barbiturates, clomiphene, androgen, dexa-estrogen, gonadotropin, oral methazone, diethylstilbestrol, digoxin, ethanol, halothane, idiopathic hirsutism-spironolactone, phenothiazines

Free testosterone in the blood serum

Approximately 2% of the testosterone circulating in the blood is in a free state. Only free testosterone is able to penetrate the cell, bind to intracellular receptors, penetrate the nucleus and modify gene transcription( that is, ultimately, to realize its biological effects).Reference values ​​of testosterone concentration in blood serum are given in the table.

Reference values ​​for free testosterone concentration in blood serum

Reference values ​​for free serum testosterone concentration

Free testosterone is independent of the concentration of CCG.Therefore, the determination of free testosterone is indicated in those situations when the content of the SSH may increase( hyperthyroidism, hyperestrogenism, pregnancy, intake of oral contraceptives or antiepileptic drugs) or decrease( hypothyroidism, obesity).

Dihydrotestosterone in the blood serum

In most androgen-sensitive tissues, testosterone is converted under the action of 5a-reductase in DHT, a more active form of androgen. Testosterone and DHT in the cell bind to the same receptor, but the affinity of testosterone to the receptor is significantly lower than that of DHT.Only DHT affects the prostate gland, skull bones and hair growth. DHT is metabolized to 3a-androstenediol-glucuronide. Reference values ​​of DHT concentration in blood serum are given in the table.

Table Reference concentration values ​​of DHT in blood serum

Table Reference concentration values ​​of DHT in blood serum

Androgens play a central role in the development of the prostate gland and ancillary in the formation of its benign hyperplasia( in persons,castrated to the full development of the prostate gland during puberty, benign hyperplasia never develops).It is established that when testosterone enters the cells of the prostate gland, it undergoes metabolic transformations. More than 95% of testosterone in the prostate gland is metabolized by the enzyme 5a-reductase in DHT, which, interacting with androgen receptors, stimulates the synthesis of specific proteins( growth factors).These growth factors cause prostate cell proliferation and

to simultaneously slow down the death of older cells. Normally, the testosterone level and the formation of DHT maintain a constant balance between the death of old and the formation of new cells. If an excess of DHT is formed, this leads to an increase in the level of growth factors and uncontrolled growth of the prostate gland - benign hyperplasia. The important role of male sex hormones in the development of benign prostatic hyperplasia is evidenced by data indicating that the use of a significant amount of alcohol leads to a decrease in the concentration of testosterone in the blood, an increase in its clearance and is combined with a decrease in the frequency of prostatectomy for this disease. At present, the important role of DHT in the development and progression of benign prostatic hyperplasia has been proved, therefore the directed decrease in its concentration in the blood has therapeutic significance.

Concentration of DHT in serum is closely related to the concentration of testosterone. The ratio of DHT / testosterone decreased during pregnancy.

Concentration of DHT in the blood is reduced with insufficiency of 5a-reductase and hypogonadism. An increase in the concentration of DHT is characteristic of hirsutism( this indicator is not used to evaluate the flow of hirsutism, since the concentrations of DHT in the blood serum do not reflect its intracellular content).