Also known as: follicle-stimulating hormone
Name: follicle-stimulating hormone
Related tests: Oestrogens, LH, Testosterone, Progesterone
Why get tested?
To assess the function of the pituitary gland, particularly in relation to fertility problems, gonadal failure, development problems or pituitary tumours
When to get tested?
When you are having difficulty getting pregnant or have irregular periods, when the doctor thinks you have symptoms of a pituitary or hypothalamic disorder or of ovarian or testicular disease, or when the doctor suspects that a child is maturing sexually too late or too early
Sample required?
A blood sample taken from a vein in the arm; sometimes a random urine sample or a 24-hour urine collection may be used
Test preparation needed?
None
What is being tested?
Follicle-stimulating hormone (FSH) is produced by the pituitary gland in the brain. Control of FSH production is a complex system involving hormones produced by the gonads (ovaries or testicles), the pituitary gland and the hypothalamus.
In women, FSH stimulates the growth and maturation of eggs (follicles) in the ovaries during the follicular phase of the menstrual cycle. The menstrual cycle is divided into the follicular and luteal phases, with a mid-cycle surge of FSH and luteinising hormone (LH). Ovulation occurs shortly after this mid-cycle hormone surge. During the follicular phase, FSH triggers the production of oestradiol by the follicle, and the two hormones work together in the further development of the egg follicle. During the luteal phase, FSH stimulates the production of progesterone. Both oestradiol and progesterone help the pituitary gland control the amount of FSH produced. FSH also helps the ovaries respond to LH. At the menopause the ovaries stop working and FSH levels rise. In men, FSH stimulates the testicles to produce mature sperm and also promotes the production of androgen-binding proteins. FSH levels are relatively constant in males after puberty.
In newborn babies and children, FSH levels rise just after birth and then fall to very low levels by 6 months in boys and 1-2 years in girls. Concentrations begin to rise again before the onset of puberty and the development of secondary sexual characteristics.
How is the sample collected for testing?
A blood sample is taken with a needle from a vein in the arm. Sometimes a random urine sample is collected but, because FSH is released in cycles, a 24-hour urine collection may be requested. Measuring the FSH produced over a 24-hour period minimises the effect of the variation in FSH levels during the day.
Is any preparation needed to ensure the quality of the sample?
No preparation is needed, but in women, for example, the sample must be collected at specific times in the menstrual cycle
How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?
How is it used?
FSH is often used together with other tests (LH, testosterone, oestradiol and progesterone) to investigate infertility in men and women. FSH levels are used to find out why a man has a low sperm count. FSH levels are also useful in investigating menstrual irregularities and in helping to diagnose pituitary disorders or diseases affecting the ovaries or testicles. In children, FSH and LH are used to diagnose delayed or early puberty.
When is it requested?
In women and men, FSH and LH are requested as part of the investigation of infertility and of pituitary or gonadal disorders.
FSH may be requested in women whose periods have stopped or become irregular, to find out whether they have reached the menopause.
In children, FSH and LH may be requested when a boy or girl does not seem to have entered puberty at the appropriate age (either too late or too early). Signs of early puberty can include:
• Breast enlargement in girls
• Growth of pubic hair
• Growth of the genitals in boys
• Start of periods in girls
Irregularities in the onset of puberty can indicate a more serious problem involving the hypothalamus, pituitary gland, gonads (ovaries and testicles) or other systems. Measuring LH and FSH can help distinguish between symptoms of benign and serious disease. Once it has been established that the symptoms are the result of real disease, further tests can be done to find the underlying cause.
What does the test result mean?
In women, FSH and LH levels can help distinguish between primary ovarian failure (failure of the ovaries themselves) and secondary ovarian failure (ovarian problems due to disorders of the pituitary gland or hypothalamus). Raised FSH and LH levels are consistent with primary ovarian failure. Some causes of primary ovarian failure are listed below.
Developmental defects:
• Failure of the ovaries to develop (ovarian agenesis)
• Chromosomal abnormalities, such as Turner syndrome
• Defects in steroid production by the ovaries, such as 17-alpha-hydroxylase deficiency
Premature ovarian failure due to:
• Radiation
• Chemotherapy
• Autoimmune diseases
Chronic failure to ovulate (anovulation) due to:
• Polycystic ovary syndrome (PCOS)
• Adrenal diseases
• Thyroid diseases
• Ovarian tumour
When a woman reaches the menopause and her ovaries stop working, FSH levels rise.
Low FSH and LH levels are consistent with secondary ovarian failure due to a pituitary or hypothalamic problem. Low blood FSH levels have been associated with an increased risk of ovarian cancer.
In men, high FSH levels are due to primary testicular failure. This may be due to developmental defects in the growth of the testicles or to damage to the testicles, as listed below.
Developmental defects:
• Failure of the gonads to develop (gonadal agenesis)
• Chromosomal abnormalities, for example Klinefelter syndrome
Testicular failure:
• Viral infection (mumps)
• Injury
• Radiation
• Chemotherapy
• Autoimmune diseases
• Germ cell tumours
Low levels are consistent with pituitary or hypothalamic disorders.
High FSH and LH levels together with the development of secondary sexual characteristics at an unusually young age indicate precocious puberty. This is much more common in girls than in boys. This early development can have several underlying causes that must be diagnosed and treated. Some of the causes are:
• Central nervous system lesions
• Hormone-secreting tumours
• Ovarian tumours or cysts
• Testicular tumours
Normal prepubertal levels of LH and FSH in children who show some signs of pubertal change may indicate a benign form of early puberty with no underlying or identifiable cause, or it may simply be a normal variant of puberty.
In delayed puberty, LH and FSH levels may be normal or lower than expected for a young person of that age. A test of the LH response to GnRH may need to be carried out, together with others, to diagnose the cause of delayed puberty. Some of the causes of delayed puberty can include:
• Gonadal failure (ovaries or testicles)
• Hormone deficiency
• Turner syndrome (chromosomal abnormality in females)
• Klinefelter syndrome (chromosomal abnormality in males)
• Chronic infections
• Cancer
• Eating disorders (anorexia nervosa)
Is there anything else I should know?
FSH levels may be raised by cimetidine, clomifene, digitalis and levodopa. FSH levels may fall with oral contraceptives, phenothiazines and hormone treatments. FSH has been seen to rise with age and in smokers.
A recent nuclear medicine scan can interfere with FSH test results
1. I can’t get pregnant. What tests do I need?
2. Why would a woman have several FSH tests and a man only one?
3. Why would a man need a test for female hormones?
4. Is there a home test for FSH?
1. I can’t get pregnant. What tests do I need?
Basic fertility tests often include measuring FSH and luteinising hormone (LH). The doctor may also ask you to record your body temperature, which rises slightly during ovulation. Other hormone tests may be carried out, as may a post-coital test (after sexual intercourse). A hysterosalpingogram (an image of the fallopian tubes) may be indicated to see whether the fallopian tubes are blocked. Your partner may be asked to provide a semen sample for analysis.
2. Why would a woman have several FSH tests and a man only one?
Several FSH tests may be carried out on a woman to get an idea of FSH concentrations over time. In women FSH concentrations are cyclical, peaking every month, while men have more stable values
3. I’m a young woman, but I’m now growing facial hair and I still don’t have regular periods. What’s wrong with me?
You may have polycystic ovary syndrome (PCOS), a hormonal problem seen in 7-10% of women and one of the main causes of infertility. In this condition the ovaries may become larger because of cysts that form inside them. Women with PCOS may also have high androgen levels and not ovulate normally. You may need laboratory tests, including FSH, LH and androgens, to make sure that PCOS is the condition causing your symptoms. A combination of medicines and hormone treatment can help relieve the symptoms.
4. Why would a man need a test for female hormones?
Men also produce FSH and LH. These hormone levels are important for male fertility. In men, FSH stimulates the testicles to produce sperm, just as in women FSH stimulates the ovaries to produce eggs. In men, LH may be measured if testosterone levels are low.
5. Is there a home test for FSH?
Yes. There is an FDA-approved self-test that measures FSH in a urine sample. It is used as an indicator of perimenopause, which is associated with rising FSH levels. For more information, see the article on home testing and the FDA website