Follicle-Stimulating Hormone (FSH)

Definition - What does Follicle-Stimulating Hormone (FSH) mean?

Follicle stimulating hormone (FSH) is a naturally occurring hormone that regulates essential reproductive health processes in both men and women.

In women, FSH controls the menstrual cycle and promotes egg development. In men, FSH levels control sperm production. FSH is crucial to the overall reproductive system, and abnormal FSH levels may cause infertility.

FertilitySmarts explains Follicle-Stimulating Hormone (FSH)

Within female bodies, FSH is the hormone that triggers an ovarian follicle, resulting in egg development. FSH stimulates preparation of the egg up until the time it is released, known as ovulation. Therefore, levels of FSH are highest in a woman’s bloodstream right up until ovulation, at which point the hormone is no longer needed, and the secretion ends.

In men, the level of FSH produced remains constant. Men’s pituitary glands are constantly releasing small amounts of hormone in order to regulate sperm development.

To determine the levels of FSH, a blood test is performed. This test is known as an FSH test, and the results indicate the level of FSH present in the body. For women, the level of FSH is analyzed along with the stage in her menstrual cycle and age in order to provide insight into her ovarian reserve and functioning. Ovarian reserve refers to the number of viable eggs she has remaining, indicating her remaining fertility potential. For men, FSH levels have no rise or fall pattern, therefore the test can be completed at any point. The FSH test will indicate the functioning of the testicles and sperm production, primarily the sperm count.

FSH tests are typically conducted as a component of infertility testing, to diagnose the cause preventing conception from occurring. Additionally, FSH may be measured to evaluate issues with menstrual periods, such as irregular periods or absent periods. An abnormal FSH level may be high or low.

In women, abnormally high levels of FSH indicate that menopause has occurred. If the woman is under the age of 40, this may indicate a premature loss of ovarian function. For men, high levels indicate the testicles are not functioning properly, possibly due to:

  • Genetic conditions or disorders
  • Dysfunctional testicles
  • Damaged testicles (drug use, cancer treatment, or excessive alcohol intake)

Alternatively, low levels of FSH may indicate:

  • Eggs or sperm are not being produced
  • A region of the brain is not functioning properly (pituitary gland, hypothalamus)
  • Excessive stress
  • Low body weight
  • The presence of a tumor on the brain

Treatment of abnormal FSH levels is dependent upon the cause and desired outcome of the individual affected.

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