FSH along with LH (luteinizing hormone), belongs to the family of gonadotropins. Pulsatile FSH and LH are secreted by the anterior pituitary in response to gonadotropin releasing hormone releasing intermittent (GnRH) from the hypothalamus. Blood levels of gonadotropic hormones are controlled by sex hormones (estrogen, progesterone, testosterone, etc.) through negative feedback on the hypothalamus.
FSH stimulates spermatogenesis in men (low levels of gonadotropin hormones can cause azoospermia). In women, FSH, along with LH, stimulates the growth and maturation of follicles and estrogen biosynthesis on a follicular level. FSH level has a maximum in the middle of the menstrual cycle (ovulatory phase), but with a smaller increase than in LH.
In simplistic terms, FSH and LH levels increases in cases where sex hormones have a deficient production (hypogonadism, Klinefelter syndrome, testicular regression, testicular feminizing syndrome, alcoholism, castration, menopause ). The level of FSH and LH is low in pituitary or hypothalamic failure, testicular tumors or adrenal secretion influencing estrogen or androgen.
The increase in basal LH ratio LH / FSH> 2, in a patient with chronic anovulation is suggestive of polycystic ovary.
Recommendations for determination of FSH:
For men: elucidation of hypothalamic-pituitary-gonadal axis dysfunctions (mainly for differential diagnosis between primary testicular failure and testicular stimulation deficit), genetic disorders with chromosomal aberrations (eg .: Klinefelter syndrome), defining testicular dysfunction, testicular feminizing syndrome.
In women: elucidating the hypothalamic-pituitary-gonadal axis dysfunctions (mainly for differential diagnosis between primary ovarian insufficiency and deficiency of ovarian stimulation), polycystic ovaries, menstrual disorders (including amenorrhea), defining phases of the menstrual cycle during evaluation for infertility, menopausal syndrome evaluation.
Method – ELISA
Reference values - dependent on age and sex.
In women the values are variable depending on the menstrual cycle:
Conversion factor: mIU / mL = IU / L.