Inhibins are heterodimeric hormones synthesized in the granulosa cells of the ovary and the "sterol" cells of the seminiferous tubules. Consists of 2 subunits: common α and β, which is specific for each type of inhibin (A and B).

Inhibin selectively inhibits the secretion of FSH by the pituitary gland (based on the principle of negative feedback), regulates folliculogenesis and spermatogenesis, has a local paracrine effect on the gonads. Inhibin synthesis reduces gonadoliberin secretion; Androgens, FSH and insulin-like growth factor-1 increase its secretion.

In girls, the level of inhibin B increases with puberty, which allows this study to identify puberty disorders. In women, it is synthesized in developing, small follicles and is characterized by marked variability in the phases of the menstrual cycle: in particular, the maximum level is observed in the early follicular phase (from the 3rd day), remains maximal until the middle of the follicular phase and decreases towards the end.

2 days after the peak of LH, a short peak is revealed again, with a further decrease in concentration. Low levels of inhibin B are observed during the luteal phase. Decreasing the number of follicles with age leads to a decrease in the level of inhibin B to a low, almost indefinite level.

In combination with FSH and AMH, inhibin B is used as one of the markers for assessing ovarian follicular reserve. Since it is produced in gonadal tissue, it is considered to be a more direct marker of gonadal activity than pituitary hormones.

Given that inhibin B is synthesized in granulosa cells, in 80–100% of cases there is a sharp increase (60-fold) in granulosa cell carcinoma of the ovary and in 55–60% of cases in cases of mucosal types of ovarian epithelial cancer, respectively. , Co-determination with CA 125 helps us identify this type of cancer in which the level of CA 125 does not change. However, normal levels of inhibin B do not completely rule out the presence of malignant tumors of the ovary.

Inhibin levels in boys increase in childhood, the concentration peak at 3 months, accompanied by a gradual decline by 10 years. Detection of inhibin B indicates the presence and functional ability of testicular tissues, and is used to determine sex in the development of gonadal pathologies and suspicious situations.

Analysis of this hormone allows us to distinguish between anorexia (congenital absence of testicles) and cryptorchidism (testicles are not present in the testis) in order to timely prescribe the necessary treatment.

Inhibin B is used in adult men as a marker of spermatogenesis and Sertol cell function, which regulate sperm maturation.

In the male body, the hormone concentration is relatively high, stable and is proportional to the volume of testicular tissue and sperm density.

Decreased concentrations of inhibin B are observed in men with oligospermia (decreased sperm count), azoospermia (absence of sperm in the ejaculate), and impaired spermatogenesis.

Simultaneous determination of FSH and inhibin B allows us to assess the adequacy of spermatogenesis.

When should we take a test for inhibin B?

Inhibin B - Ovarian reserve marker (with FSH and AMH). Granulocyte ovarian cancer marker.

In women:

• Diagnosis of pubertal disorders;
• Complex examination of women to determine the causes of infertility, menstrual disorders, premature ovarian failure and to assess ovarian reserve;
• Determining the time of transition to ART in the treatment of infertility.
• Predicting the effectiveness of infertility treatment with various ART methods;
• Predicting the effectiveness of ovarian stimulation in IVF cycles;
• Diagnosis of mucinous type of ovarian granulocyte and epithelial tumors, monitoring the effectiveness of treatment, evaluation of recurrence and metastases. (With CA-125).

In men:

• Diagnosis of pubertal disorders;
• Complex examination of infertility, disorders of spermatogenesis.

How to prepare for the test?

Testing is preferred Fasting.

women: The patient should indicate the date of the last menstrual period. It is best to determine on the 3rd day of the menstrual cycle (when the peak level is observed).

Research material

Venous blood

Possible interpretation of the results

Increase in inhibin B levels:

• Polycystic ovary syndrome;
• Granulocyte ovarian cancer;
• Mucinous type of ovarian epithelial cancer;
• Antiandrogen therapy (in men).

Decreased inhibin B levels:

women:

• Decreased age-related follicular reserve of the ovary;
• During menopause;
• Premature ovarian failure;
• Surgical menopause;
• Antitumor chemotherapy.

men:

• Disruption of spermatogenesis, especially in its early stages;
• Hyper- and hypogonadotropic hypogonadism.