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To evaluate fertility issues, the health of your reproductive organs (ovaries or testicles), or pituitary function
In children, to evaluate early or delayed puberty
For women, when you are having difficulty getting pregnant or are having irregular or no menstrual periods
For men, when your partner cannot get pregnant, or you have a low sperm count, low muscle mass or decreased sex drive
When your healthcare practitioner thinks that you have symptoms of a pituitary disorder or hypothalamic disorder
When a healthcare practitioner suspects that a child has delayed or earlier than expected puberty
A blood sample is drawn by needle from a vein.
No test preparation is needed, but a woman's sample should be collected at specific times during her menstrual cycle.
Follicle-stimulating hormone (FSH) is a hormone associated with reproduction and the development of eggs in women and sperm in men. This test measures FSH in the blood.
FSH is made by the pituitary gland, a small organ located in the center of the head behind the sinus cavity at the base of the brain. Control of FSH production is a complex system involving the hypothalamus in the brain, the pituitary gland, and the hormones produced by the ovaries or testicles. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary to release FSH and luteinizing hormone (LH), a closely related hormone also involved in reproduction.
As a woman ages and menopause approaches, ovarian function wanes and eventually ceases. As this occurs, FSH and LH levels rise.
Disorders affecting the hypothalamus, pituitary, and/or the ovaries or testicles can cause the production of too much or too little FSH, resulting in a variety of conditions such as infertility, abnormal menstrual cycles, or early (precocious) or delayed puberty.
In women, FSH levels are also useful in:
In men, FSH levels are used to help determine the reason for a low sperm count.
In children, FSH and LH are used to help diagnose delayed or precocious (early) puberty. Irregular timing of puberty may be an indication of a more serious problem involving the hypothalamus, the pituitary gland, the ovaries or testicles, or other systems. The measurement of LH and FSH may differentiate between normal patterns of development and true disease. Once it is established that symptoms are a result of true disease, further testing can be done to identify the underlying cause.
For a woman, an FSH test may be ordered when she is having difficulty getting pregnant, has irregular or an absence of menstrual periods, or sometimes when it is suspected that she has entered menopause.
For a man, the test may be ordered when his partner cannot get pregnant, when he has a low sperm count, or when he has low muscle mass or decreased sex drive, for example.
In both women and men, testing may be ordered when a healthcare practitioner suspects that a pituitary disorder is present. A pituitary disorder can affect the production of several different hormones, so there may be signs and symptoms in addition to some of those listed above. They can include fatigue, weakness, unexplained weight loss, and decreased appetite to name a few.
In children, FSH and LH may be ordered when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon). Signs of puberty may include:
As part of an infertility workup, a high or low FSH is not diagnostic but provides a piece of information on what may be the cause. For example, a hormone imbalance may affect a woman's menstrual cycle and/or ovulation. A healthcare practitioner will consider all the information from the workup to establish a diagnosis.
FSH and LH levels can help to differentiate between a condition affecting the ovaries themselves (primary) and dysfunction of the ovaries due to disorders of either the pituitary or the hypothalamus (secondary).
High levels of FSH and LH are consistent with conditions affecting the ovaries themselves. Some examples include:
Damage to the ovaries due to:
Underlying conditions that affect ovary function, such as:
When a woman enters menopause and her ovaries stop working, FSH levels will rise.
Low levels of FSH and LH are consistent with a pituitary disorder or problem with the hypothalamus.
Low FSH serum levels have been associated with increased risk of ovarian cancer.
High FSH levels are due to conditions affecting the testicles themselves. Some examples include:
Low levels are consistent with pituitary or hypothalamic disorders. See the article on Pituitary Disorders for more information.
Higher levels of FSH and LH than expected for age plus the development of secondary sexual characteristics at an unusually young age are an indication of early puberty. This is much more common in girls than in boys. This premature development is usually due to a problem with the central nervous system and can have a few different underlying causes. Examples include:
Normal prepubescent levels of LH and FSH in children exhibiting some signs of puberty may indicate a condition called "peripheral precocious puberty." The signs and symptoms are brought on by elevated levels of the hormones estrogen or testosterone. This may be caused by:
Normal FSH and LH levels with a few signs of puberty (e.g., development of pubic hair and acne) may signal a previous environmental exposure to agents, such as testosterone cream or gel, or may be a normal variation of puberty.
In delayed puberty, LH and FSH levels can be normal or below what is expected for a youth within this age range. Examples of some causes of delayed puberty include:
Basic tests for infertility often include measuring FSH and luteinizing hormone (LH) levels. Your healthcare provider may also ask you to keep track of your body temperature, which rises slightly during ovulation. Other hormonal tests as well as a postcoital (after intercourse) examination may be done. A hysterosalpingogram (image of fallopian tubes) may be ordered to see whether your fallopian tubes are blocked. Your partner may be asked to give a specimen of semen for analysis.
Men also produce FSH and LH. These hormone levels are important for male reproduction too. In men, FSH stimulates the testicles to produce sperm just as in women FSH stimulates the ovaries to produce eggs. In men, LH can be measured if testosterone levels are low.
Yes. There is an FDA-approved self-test that measures the level of FSH in a urine sample. It is used as an indicator of menopause and perimenopause, which are associated with a rise in FSH levels. For more information, see this FDA website.
FSH results can be increased with use of certain drugs, including cimetidine, clomiphene, digitalis, and levodopa. FSH results can be falsely elevated in people who are taking large doses of biotin as this can interfere with immunoassays. FSH results can be decreased with oral contraceptives, phenothiazines, and hormone treatments. FSH will also be low when women are pregnant.
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