Blood Test: Follicle Stimulating Hormone (FSH)





Blood Test: Follicle Stimulating Hormone (FSH)
What It Is



Follicle stimulating hormone (FSH) is produced by the pituitary
gland, a pea-sized gland near 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 more 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.

Why It's Done



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.

Preparation



No special preparations are needed for this test. It may help to have
your child wear a short-sleeve shirt on the day of the test to allow
easier access for the technician who will be drawing the blood.The Procedure



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back of the hand) and blood is withdrawn and collected in a vial or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.




What to Expect



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.Getting the Results



The blood sample will be processed by a machine. The results usually are available after a day or two.

Risks



The FSH test is considered a safe procedure. However, as with many
medical tests, some problems can occur with having blood drawn:

• fainting or feeling lightheaded
  
• hematoma (blood accumulating under the skin causing a lump or bruise)
  
• pain associated with multiple punctures to locate a vein
  

Helping Your Child



Having a blood test is relatively painless. Still, many children 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



If you have questions about the FSH test, speak with your doctor.