Why this test?
For the diagnosis of granulosa cell and mucinous ovarian tumors.
To monitor patients with ovarian neoplasms.
To assess the ovarian reserve of the ovaries.
To predict the result of artificial insemination.
To assess testicular function and spermatogenesis.
For differential diagnosis of cryptorchidism and anarchy.
For the diagnosis of disorders of sexual development.
In what cases is it prescribed?
If granulosa cell or mucinous ovarian cancer is suspected.
Before, during and after treatment of ovarian neoplasms.
With premature puberty (or its delay).
With disorders of spermatogenesis in men.
With infertility in men and women.
With abnormalities of the development of gonads in boys.
When planning artificial insemination.
In case of ambiguous sexual characteristics in children (the analysis can be prescribed in complexes with determination of the level of other sex hormones and instrumental ones diagnostic methods).
Avoid taking estrogens and androgens within 48 hours before the testing.
The testing is recommended to be carried out on the 3rd-4th day of the menstrual cycle.
Inhibin B is a glycoprotein that is synthesized in the Sertoli cells of the seminiferous tubules of the testicles of men and the granulosa cells of the follicles of the ovaries of women. It belongs to the transforming growth factor B superfamily.
The active form of the hormone consists of alpha and beta subunits joined by disulfide bonds. Inhibin B suppresses the formation of follicle-stimulating hormone (FSH) in the pituitary gland by the principle of negative feedback and performs a local paracrine effect in the testicles and ovaries. The synthesis of inhibin decreases under the influence of gonadoliberin. Androgens, FSH and insulin-like growth factor - 1 increase its secretion. In the female body, inhibin B is synthesized by antral (secondary) ovarian follicles. In girls, the concentration of inhibin B in the blood increases as puberty progresses.
Accordingly, determining the level of this hormone is important in diagnosing premature puberty and assessing the maturity of the gonads. When women reach reproductive age, the concentration of inhibin B changes depending on the menstrual cycle. It begins to rise in the early follicular phase of the menstrual cycle, reaches a maximum in its middle and remains low in the luteal phase.
There is also a short-term increase in the concentration of inhibin 2 days after the peak increase in the amount of luteinizing hormone in the middle of the cycle, which corresponds to the period of ovulation. It is believed that inhibin B is of great importance in the regulation of the level of FSH in the early and middle period of the follicular phase.
With age, the number of follicles in a woman's ovary decreases and the synthesis of inhibin B decreases. In the early premenopausal period, the level of inhibin B in the follicular phase of the cycle decreases earlier than the level of estradiol and inhibin A.
In this regard, the level of inhibin B in the first phase of the menstrual cycle may indicate the rapid onset of menopause. In the postmenopausal period, the hormone is determined in a very low concentration (less than 5 pg/ml) or is not determined at all. Increased concentrations of inhibin B in postmenopausal women require the exclusion of granulosa cell or mucinous ovarian carcinoma, for which this hormone is a specific marker. In the above-mentioned ovarian neoplasms, a more than 60-fold increase in the concentration of inhibin B is possible. Joint analyzes of CA 125 and inhibin B with additional instrumental research methods allow to identify the tumor and control the treatment process.
Determining the amount of inhibin B and other sex hormones can be useful in the study of the ovarian reserve - the number of eggs and follicles in the ovaries capable of growth and development. The more follicles in the ovary, the higher the level of inhibin B.
With natural (due to age changes) or premature exhaustion of the ovaries, the ability to complete ovulation, natural pregnancy and normal bearing of the fetus is lost. In this regard, the level of inhibin B is often determined to assess the possibility of a normal pregnancy in a woman of a more mature age and / or forecast the effectiveness and feasibility of assisted reproductive technologies (in vitro fertilization - IVF, insemination with donor sperm). FSH, inhibin B and anti-Mullerian hormone are examined to assess ovarian reserve on the third day of the menstrual cycle. In the male body, inhibin B is the primary regulator of FSH secretion.
The level of the hormone is increased in childhood, the peak concentration occurs at three months, then it gradually decreases, reaching a minimum in 6-10 years. In boys, the determination of inhibin B indicates the presence and functional capacity of testicular (testicular) tissue and is used to diagnose abnormalities in the development of the gonads and determine gender in doubtful situations.
The analysis of this hormone allows to differentiate anorchism (congenital absence of testicles) and cryptorchidism (failure of the testicles to descend into the scrotum) and prescribe the necessary treatment. Inhibin B is used as a marker of spermatogenesis in sexually mature men and the function of Sertoli cells, which regulate sperm maturation.
In the male body, the concentration of the hormone is at a relatively high, stable level and is proportional to the volume of testicular tissue and sperm density. A reduced concentration of inhibin B is found in men with oligospermia (reduced amount of sperm), azoospermia (absence of sperm in the ejaculate) and impaired spermatogenesis. Simultaneous determination of FSH and inhibin B allows to assess the adequacy of spermatogenesis.