Are you curious to know which male hormone inhibits the secretion of FSH? You may think this is a task for your doctor, but if you are eager to become pregnant and want to be sure everything will be in order, then you probably feel the need to know everything there is to know about your future pregnancy.
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Who Produces Follicle Stimulating Hormone?
Follicle stimulating hormone, or FSH, is a gonadotropin produced and released into the bloodstream by the pituitary gland in a much more complex process known as hypothalamic-pituitary-gonadal axis. Follicle stimulating hormone is an essential hormone for the sexual development and fertility of both sexes.
Which Are the Normal Values of FSH?
There are certain normal parameters in which the results must fit for determining the hormone`s level in blood. But the results depend on several factors, such as health status or age:
- Fertile women – who have menstruation (follicular phase – 2 = 15 IU/L; ovulation – 22-57 IU\L; luteal phase – 1/16 IU/L);
- Postmenopausal women – 14-52 IU/L;
- Men – 1-8 IU/L.
The Role & Importance of FSH
Follicle stimulating hormone is very important in developing the sexual organs at puberty for both women and men. If at children the hormone`s level is low, as they reach puberty, the brain starts producing GnRH, the hormone which will start specific changes for this period. Also, GnRH transmits towards the pituitary gland the message of producing FSH and LH (luteinizing hormone). These 2 hormones signal further to the testicles and ovaries to produce testosterone, respectively estrogen – hormones responsible for the development and maturation of sexual organs.
When menstrual cycle is concerned, FSH has the main role of producing ovulation. After menstruation, the FSH level starts to grow and stimulate the development of ovarian follicles. It also helps mature the eggs which will be released at ovulation. Thus, it stimulates the egg`s development as well as the cells around it which produce hormones necessary in sustaining the future pregnancy. At the same time, FSH stimulates the ovaries in producing estrogen and the endometrium starts to thicken, thus preparing the uterus for a possible pregnancy. If the ovulation has taken place, the FSH level decreases again.
At men, FSH acts on the testicles, stimulating the sperm production. Unlike for women, at men the level of FSH stays constant and doesn`t register variations if it isn`t affected by certain medical conditions or imbalances.
Follicle stimulating hormone is one of the main hormones used in infertility treatments due to its capacity of stimulating the egg production and its maturation. Injectable treatments with this hormone target the follicle artificial stimulation.
What Imbalances Can FSH Produce?
The FSH values vary during the menstrual cycle, reason for which the testing of this hormone is recommended to be made at 3rd day of the menstrual cycle. If the values are too high or low, it`s recommended a re-testing to eliminate the possibility of an occasional variation.
A low level of FSH during puberty at girls leads to an incomplete development of ovaries and their impossibility to function properly, meaning a risk of infertility. Also, if generally during the first part of the menstrual cycle there isn`t an increase of FSH, ovulation won`t take place. At men, the effect of a low level of FSH will lead to a delay of puberty, and for adults will have an impact in the amount of sperm produced, which again, leads to infertility.
On the other hand, a high level of FSH can signal certain dysfunctions of ovaries or testicles. For instance, if these organs don`t manage to produce sufficient estrogen or testosterone, the pituitary gland won`t be able to regulate the production of FSH and LH, which will lead to an increase of these hormones. Such a situation happens in case of medical conditions such as Kallmann syndrome at men and Turner syndrome at women.
Women with an increased level of follicle stimulating hormone have high chances to confront themselves with fertility issues. In such a case there may be recommended an aggressive reproductive treatment or in vitro fertilization.
A natural increase of the level of FSH takes place in women when they approach menopause, which signals a decrease of ovary functions. While the woman gets older, the number of eggs from the ovaries and quantity of estrogen become smaller, that`s why the pituitary gland tries to balance the situation by producing more FSH.
Which Male Hormone Inhibits the Secretion of FSH?
Inhibin is a protein substance, produced by men only in the testicles, which has an inhibitory role on FSH. Its low levels might indicate a blockage or another defect localized in the seminiferous tubules.
Inhibin is produced by the Sertoli cells in men and by the ovarian follicle`s granulose cells at women. The main function of this hormone consists in regulating gametogenesis through a mechanism of negative feed-back exerted on the production of FSH. Numerous studies attest to the usefulness determination of inhibin as an endocrine marker for monitoring the gonadal function of both sexes. – Find out about this!
As mentioned above, the female fertility decreases with age due to a reduced number of ovarian follicles (ovarian reserve). Because inhibin is a direct product of the small follicles in development, it constitutes an important indicator of the ovarian reserve.
Normal Values of Inhibin
- 120-400 ng/L
- 1-2 days of the menstrual cycle: 15-70 ng/L
- 3-5 day menstrual cycle: 45-120 ng/L
- Late follicular phase: 30-90 ng/L
- Ovulation: 80-200 ng/L
- Luteal phase <50 ng/L
- Postmenopausal / ovariectomy <10 ng/L
In day 3 of menstrual cycle, a value of >45 ng/L indicates a normal ovarian reserve.
Decreases of Inhibin
In men, a value of <60 ng/L indicates a testicular dysfunction with impaired spermatogenesis (for example Kallmann syndrome, Klinefelter syndrome).
In men, inhibin constitutes a direct marker of Sertoli cell function and spermatogenesis. It has been found that serum levels of inhibin correlate with the testicular volum and sperm density. Thus, men with an absent or negligible sperm production shows very low values of inhibin. The combined determination of FSH and inhibin represents a better indicator of spermatogenesis than their isolated testing.
Women with very low levels of inhibin (<20 ng/L) often shows a very weak ovarian response, so they must be counseled to choose an oocyte donation or adoption.
Increases of Inhibin
In granulose tumors are registered very high values of inhibin, which is a useful test for diagnosis as well as for detecting tumor recurrence.