Follicle-stimulating hormone (FSH) is one of the gonadotropins, a key hormone involved in the reproductive function and crucial for the woman’s fertility.
Follicle-stimulating hormone function in the woman’s body
Follicle-stimulating hormone is secreted from the beta-cells by the anterior portion of the pituitary gland (known as the adenohypophysis) stimulated by the gonadotropin-releasing hormone produced by the hypothalamus. FSH is the main promoter of the follicular maturation.
The receptors to FSH are localized exclusively on the granulosa cells, therefore, its action is accomplished via binding to the FSH receptors. In response to FSH aromatase activity is induced and androstenedione is converted to estradiol.
FSH controls the production of inhibin and induces the expression of LH receptors in granulosa cells of the large follicles. Follitropin saves several small follicles from the destruction by the apoptosis (the process of programmed cell death) and stimulates their maturation, whereas few weeks later FSH promotes the further growth of the dominant Graafian follicle and the recruitment of the next generation of the follicles that will grow during the following menstrual cycles.
Of note, as one of the gonadotropins, the FSH is involved in the process of the development of the reproductive system, period of puberty and the development of secondary sex characteristics.
When a woman gets older and reaches the age of menopause the number of recruited follicles each cycle diminishes, the FSH levels rise, whereas simultaneously the FSH receptors gradually reduces until there are no FSH receptors at all.
Physiologic effects of FSH
Follicle-stimulating hormone as one of gonadotropins plays a crucial role in the functioning of the human’s reproductive system.
- Stimulates the growth and maturation of the ovarian follicles containing oocytes, especially the Graafian follicle preparing it to the ovulation – it means that this hormone is the one which controls the development of the oocyte which later will be released for the successful conception;
- In the presence of luteinizing hormone, FSH stimulates secretion of estrogen by the growing follicles;
- Promotes the endometrial changes typical for the proliferative phase of the menstrual cycle – secretion of FSH helps to restore and grow the inner lining of the uterus after the periods;
FSH as a medicine
Follicle-stimulating hormone is used as a medicine to treat infertility except cases of primary ovarian failure. The medication is injected under the skin or directly into a muscle. The administration of FSH enables ovulation if the woman’s own hormonal production is insufficient to stimulate the maturation of the follicle and induce the ovulation.
FSH is prescribed for:
- Female infertility, unless primary ovarian failure was detected;
- Stimulation of the oocyte development for in-vitro fertilization (IVF);
This medication shouldn’t be used by the women who are allergic to it or any other Gonadotropin hormonal preparations; have primary ovarian failure; ovarian cysts; abnormal uterine bleeding; thyroid or adrenal gland, pituitary abnormalities; any tumor of the reproductive system; bleeding disorder.
FSH is contraindicated for pregnant women as it may harm the fetus causing birth defects.
Side effects of FSH include:
- Nausea, vomiting, diarrhea, bloating;
- Shortness of breath;
- Weight gain;
- Abdominal pain;
- Pelvic pain;
- Skin rash;
- Signs of severe allergic reaction: swelling of the face, lips, throat, difficulties breathing, fast heart rate, hypotension etc.