Follicle-Stimulating Hormone Test (FSH Test)

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

A follicle-stimulating hormone (FSH) test is a blood measurement of the levels of the hormone FSH that is typically used for the work up and diagnosis of fertility-related disorders. FSH is a brain-secreted hormone with the primary function of stimulating the male testes and female ovary into sperm and egg production. Levels of follicle-stimulating hormone rise and fall depending on age or the stage of reproduction.

Persistently high or low levels are associated with various infertility conditions such as polycystic ovary syndrome (PCOS), premature menopause, and chromosomal abnormalities such as Turner’s syndrome.

FertilitySmarts explains Follicle-Stimulating Hormone Test (FSH Test)

Follicle-stimulating hormone (FSH) is produced by the anterior pituitary gland in the brain. At puberty, FSH in a sense awakens the immature eggs or sperm that have been dormant within the ovary and testes and stimulates ovulation and sperm maturation respectively.

Eggs within the ovary also produce the hormone, inhibin B, which lowers FSH when the egg has been ovulated. As a woman moves towards menopause, a stage where there are an inadequate number of eggs capable of ovulation, the lack of inhibin B creates a persistently elevated level of FSH; the state of menopause and infertility.

Due to the fact that FSH levels rise and fall depending on the phase of menstrual cycle, a baseline level is generally established by testing three to five days after menstruation. At this point of the cycle, FSH will be closer to baseline as the cycle is further away from ovulation, where it is at its highest.

Some women undergo premature menopause or premature ovarian failure (POF) where they have elevated FSH due to the dysfunction or removal of the ovary and in some cases, as hormones tend to be on/off switches for other hormones, there is a hormonal influence. Women who undergo chemotherapy due to cancer may have POF as a consequence.

A low-level of FSH also leads to infertility; in hypopituitarism, the anterior pituitary gland does not produce follicle-stimulating hormone and consequently, eggs or sperm are not prepared for ovulation or maturation.

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