Follicle stimulating hormone (FSH) is produced by the pituitary gland, a pea-sized gland in the brain that plays an important role in sexual development. An FSH test measures the level of this hormone in the bloodstream.
In kids, FSH levels are normally low. As puberty approaches (usually between ages 10 and 14), the brain produces gonadotropin-releasing hormone (GnRH), which starts the changes toward sexual maturity. GnRH signals the pituitary gland to release two puberty hormones into the bloodstream: FSH and luteinizing hormone (LH). Doctors often order a test for LH when ordering a blood test for FSH.
In boys, FSH and LH work together to get the testes to begin producing testosterone, the hormone responsible for the physical changes of puberty and the production of sperm.
In girls, FSH and LH prompt the ovaries to begin producing the hormone estrogen, which causes a girl's body to mature and prepares her for menstruation.
Because FSH and LH work so closely with each other, doctors often order these tests together, as well tests for testosterone (the male sex hormone) and estradiol (a form of estrogen, the female sex hormone). Taken together, the results can often provide a more complete picture of a child's sexual maturation.
Doctors may order an FSH test if a boy or girl appears to be entering puberty earlier or later than expected. High levels are associated with precocious (early) puberty, while low levels may indicate a delay in sexual development.
The test may also be used to check for damage or disease of the testes or ovaries, pituitary gland, or hypothalamus, an almond-sized area of the brain that links the nervous system with the hormone-producing endocrine system.
In adults, FSH levels can also help doctors evaluate fertility issues and menstrual problems.
No special preparations are needed for this test. On the day of the test, having your child wear a T-shirt or short-sleeved shirt can make things easier for the technician drawing the blood.
A health professional will clean the skin surface with antiseptic, and place an elastic band (tourniquet) around the upper arm to apply pressure and cause the vein to swell with blood. Then a needle is inserted into a vein (usually in the arm inside of the elbow or on the back of the hand) and blood is withdrawn and collected in a vial or syringe.
After the procedure, the elastic band is removed. Once the blood has been collected, the needle is removed and the area is covered with cotton or a bandage to stop the bleeding. Collecting the blood for this test will only take a few minutes.
Collecting a sample of blood is only temporarily uncomfortable and can feel like a quick pinprick. Afterward, there may be some mild bruising, which should go away in a few days.
The blood sample will be processed by a machine. The results usually are available after a day or two.
The FSH test is considered a safe procedure. However, as with many medical tests, some problems can occur with having blood drawn, like:
Having a blood test is relatively painless. Still, many kids are afraid of needles. Explaining the test in terms your child can understand might help ease some of the fear.
Allow your child to ask the technician any questions he or she might have. Tell your child to try to relax and stay still during the procedure, as tensing muscles and moving can make it harder and more painful to draw blood. It also may help if your child looks away when the needle is being inserted into the skin.
If you have questions about the FSH test, speak with your doctor.
Reviewed by: Yamini Durani, MD
Date reviewed: September 2014
|American Medical Association (AMA) The AMA has made a commitment to medicine by making doctors more accessible to their patients. Contact the AMA at: American Medical Association|
515 N. State St.
Chicago, IL 60610
|American Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.|
|American Society of Hematology This group provides information relating to blood, blood-forming tissues, and blood diseases.|
|Hormone Foundation The Hormone Foundation's mission is to serve as a resource for the public by promoting the prevention, treatment, and cure of hormone-related diseases.|
|Blood Test (Video) These videos show what's involved in getting a blood test and what it's like to be the person taking the blood sample.|
|Blood Test: Testosterone A testosterone blood test may be done if a boy appears to be entering puberty earlier or later than expected, or to check for damage or disease of the testes or ovaries, adrenal glands, or pituitary glands.|
|Blood Test: Luteinizing Hormone (LH) A luteinizing hormone (LH) test measures the level of this hormone in the bloodstream. LH plays an important role in sexual development.|
|Blood Test: Estradiol Estradiol is the most important form of the hormone estrogen. Doctors may order an estradiol test if a girl appears to be entering puberty earlier or later than expected, or to evaluate menstrual problems.|
|Blood Test: Dehydroepiandrosterone-Sulfate (DHEA-S) Doctors may order a DHEA-S test if boys or girls show signs of sexual development earlier than expected. It can rule out certain diseases of the testes or ovaries, or help diagnose damage or disease of the pituitary gland.|
|Delayed Puberty Concerned about your growth or development? Puberty can be delayed for several reasons. Luckily, doctors usually can help teens with delayed puberty to develop more normally.|
|Endocrine System Although we rarely think about them, the glands of the endocrine system and the hormones they release influence almost every cell, organ, and function of our bodies.|
|Precocious Puberty Precocious puberty - the onset of signs of puberty before age 7 or 8 in girls and age 9 for boys - can be physically and emotionally difficult for children and can sometimes be the sign of an underlying health problem.|
|Getting a Blood Test (Video) A blood test might sound scary, but it usually takes less than a minute. Watch what happens in this video for kids.|
|Understanding Puberty Puberty was awkward enough when you were the one going through it. So how can you help your kids through all the changes?|
|Why Does Puberty Sometimes Happen Early? Find out what the experts say.|
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