Follicle-stimulating hormone (FSH) is a hormone that is produced by the hypothalamic-pituitary system, more precisely - in the pituitary. The regulation of its production is carried out by the hypothalamus, and the concentration of FSH directly depends on the level of sex hormones in the blood.
With a slight decrease in their concentration, stimulation of FSH formation occurs, and at a high level - the synthesis of follicle-stimulating hormone decreases. Also reduces the synthesis of FSH inhibin-B, which is in the cells of the ovaries and in the seminiferous tubules of men.
Features of hormone production
The synthesis of FSH is not a constant, but a pulsating character. Thus, when the synthesized follicle-stimulating hormone is isolated into the female blood, its concentration rises sharply and exceeds the necessary norm of 2, and even 2.5 times. Then the level gradually decreases. The highest concentration is observed in the follicular stage of the menstrual cycle.
FSH levels in different periods of a woman's life
The content of follicle-stimulating hormone in the blood of any woman does not have a constant value and is normally within the limits of 1.7-135 IU / l.
So the content of this hormone in the female blood depends on the specific stage (phase) of the menstrual cycle. In the follicular phase, FSH is normally 3.49-13 IU / L, in luteal it decreases - 1.69-7.7. The greatest concentration of the hormone reaches during ovulation - 4.69-22 IU / l. During the current pregnancy, the concentration of FSH decreases rather sharply, and reaches a concentration of 0.01-0.3 IU / L.
During the postmenopausal period, the content of FSH increases, which is due to inhibition of the synthesis of estradiol and progesterone. In this period, the concentration of FSH reaches 26-135 IU / l.
The follicle-stimulating hormone content is below the norm, leading to the development of:
- the Callman syndrome;
- lack of hormone production by the pituitary gland;
- tumors of the ovaries, testicles.
In turn, increasing the concentration of follicle-stimulating hormone above the norm, can lead to such diseases as:
- diseases of the gonads;
- a pituitary tumor;
- ovarian cyst;
- underdevelopment of the gonads;
- premature puberty.
FSH, synthesized in the female body, promotes the maturation of follicles and ensures their preparation for the ovulation process. This hormone directly regulates the first phase of the entire menstrual cycle, the follicular cycle. Under its influence, the follicle significantly increases in size and begins to produce estradiol. At the end of the follicular phase, the concentration of FSH sharply increases. Then the follicle bursts, and from it a mature egg leaves the peritoneal cavity, that is, the process of ovulation takes place.
During the 2nd phase of the cycle, luteal, FSH promotes direct synthesis of progesterone. When a woman reaches the age of 45-50 years, menopause occurs, in which estradiol and progesterone are no longer produced by the ovaries, which leads to an increase in the concentration in the body of FSH.
FSH is contained in men, but at a much lower concentration. This hormone starts the process of spermatogenesis in young men. It is FSH that contributes to the normal development of male seminiferous tubules and increases the level of the hormone testosterone. In addition, follicle-stimulating hormone is involved in the formation of spermatozoa and during the maturation of sperm. The level of this hormone in men increases dramatically, when the body shows a decrease in the functional activity of the testes.
A high concentration of FSH is observed when babies are born. At boys it decreases for half a year, and at girls - reaches norm or rate for 1-1,5 years. The next time its content increases only when reaching the transition age, when FSH regulates the process of puberty.