FSH, or Follicle Stimulating Hormone, is produced within the pituitary gland of the body and plays a large role in the fertility of an individual. FSH has different effects in the two sexes and is a key hormone in the production of reproductive material.

Measuring the amounts of FSH in the body, as well as measuring other hormones such as LH (Luteinizing Hormone), progesterone, and estrogen, can help a reproductive endocrinologist determine why a couple may be infertile.


Within a female, FSH governs the production of steroids within the ovary during the proper menstrual phases. If the FSH levels are correct, the ovary will produce estradiol during the follicular phase and progesterone during the luteal phase. A surge of FSH in the body during the middle of a menstrual cycle combining with a surge in LH will trigger proper ovulation for a woman.

Within a male, FSH stimulates the Sertoli cells to produce an abundance of ABP (Androgen-binding protein). This protein stimulates spermatogenesis within the male. In certain periods of production, Sertoli cells will produce inhibin within the body with serves to shut off the signaling to the pituitary. This decreases FSH secretion within the male to prevent an overproduction of semen.


Measuring FSH within the body is a direct indicator of how the sex organs are functioning. If the FSH levels are incorrect, it is a good sign that one or more steps in the genesis of sperm (or in the stimulation of ovulation), has gone wrong leading to an increased chance of fertility complications.

Follicle Stimulating Hormone levels remain almost constant throughout a man’s adult life and fluctuate during a woman’s menstrual cycle. FSH levels are at their highest for a woman just before she ovulates, as this surge in the hormone triggers the body to release the egg.


For a couple who is having difficulty conceiving, it may be ideal to undergo an FSH test to determine if the hormone is working properly within the body. Since low levels of FSH will cause the body to not produce the required genetic material (sperm in the male, releasing eggs in a female), testing these levels is often the first step in determining infertility. It is also a key factor in the identification of menopause for a woman, as the body at this point will not be able to produce enough FSH to stimulate ovulation.

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