What is FSH?

FSH stands for follicle-stimulating hormone. It’s a gonadotropin, which is a hormone secreted by the pituitary gland. Gonadotropins stimulate activity in the gonads (ovaries and testicles), facilitating important reproductive processes in both men and women. An insufficient amount of FSH in either gender can lead to infertility issues. FSH in women affects the health of ovarian follicles, which lead to the release the woman’s egg during ovulation.

How does FSH work in the body?

FSH is produced and released based on the level of a number of other hormones released by the ovaries and testicles. This system, known as the hypothalamic–pituitary–gonadal axis, controls all activity in these parts of the body.

Nerve cells in the hypothalamus notice when FSH levels fall at the end of a woman’s menstrual cycle. When this happens, additional gonadotrophin-releasing hormone stimulates the release of additional FSH and other hormones into the blood stream. The increase in FSH leads to follicle growth in the ovary. As the follicle grows, it eventually releases enough FSH to stimulate an egg to release from a mature follicle.

What is an FSH levels test?

If your doctor suspects your FSH levels are off, they may order an FSH levels test. This test measures the amount of FSH in your blood. This test hopes to uncover underlying causes for symptoms related to reproductive problems. The most common reasons your doctor may order a test of your FSH levels are to assess infertility issues or irregular menstrual cycles or to diagnose pituitary gland disorders or a diseases involving the ovaries.

The FSH levels test is simple blood work. You will likely be asked to get tested as a certain point in your menstrual cycle as instructed by your doctor. Usually it’s at the start (within one or to days) of beginning your menstrual cycle.

What information does my doctor need before an FSH levels test?

Before you get your FSH levels test, you should share any prescription or nonprescription medications, dietary supplements and vitamins you are taking with your doctor. If you are using any kind of birth control, including an IUD or birth control pills or patch, let your doctor know that as well as hormonal birth control options can affect your results.

Existing medical disorders should also be shared. Specifically, ovarian cysts, unusual vaginal bleeding, uncontrolled thyroid disease and sex-dependent hormone tumors can be closely associated with FSH levels.

What happens during an FSH levels test?

Testing for FSH levels is a simple process. A blood sample will be taken, most likely from your arm. The risks involved are similar to other blood tests and include dizziness, bruising, pain (usually subsides quickly), redness where the needle was inserted and a small risk of infection. There is no need to worry about this very routine process.

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What do varying FSH levels mean?

Both gender and age affect FSH levels. FSH levels also fluctuate based on where a woman is in her menstrual cycle. The reference range varies slightly for each lab, which is why you should always review results with your doctor.

High FSH levels in women potentially indicate:

  • Menopause
  • Ovarian failure or loss of ovarian function
  • Chromosomal abnormality (For example, Turner’s syndrome, which happens when some or all of a female’s X chromosome is missing)
  • Polycystic ovarian syndrome (A condition that causes a woman’s hormones to be imbalanced, leading to ovarian cysts)

Heightened FSH levels can also imply that less good quality eggs and embryos are being produced and available for fertilization. Age is the most common reason for this to happen. Fertility declines with age as less eggs mature in the ovaries and the quality of those that do mature is less than when you were younger.

Hormone tests like the one that tests for FSH are often used in conjunction with other tests as hormone levels can fluctuate so drastically in each person. If high FSH levels are found, your doctor may also consult your levels of progesterone, luteinizing hormone and estradiol, all of which help determine a woman’s “ovarian reserve.” Ovarian reserve refers to the age-related fertility potential of a woman. If your FSH levels are high, it may indicate that your chances of conceiving are lower than average for your age. This does not mean you’re infertile, but can indicate that becoming pregnant may be difficult.

Low FSH levels in women potentially indicate:

  • You are not producing eggs
  • The pituitary gland or hypothalamus are not function correctly
  • A tumor is inhibiting the brain’s production of FSH

FSH do not often paint the whole picture, but rather serve as an indicator for further testing. You may be asked to track your body temperature as it may rise when you are ovulating. A fallopian tube scan may also be ordered to look for blockages preventing an egg from reaching the uterus.