What It Is
An estradiol test measures the level of the hormone estradiol in the bloodstream.
Estradiol plays an important role in sexual development: It's the most important form
of the hormone estrogen. In sexually mature females, it's produced mainly by the ovaries,
and in smaller amounts by the adrenal glands. Estrogen is also produced by the placenta
during pregnancy. Sexually mature males have much lower blood levels of estradiol,
which are produced by the testes and adrenal glands.
In young girls, estradiol levels are normally low. As puberty approaches, usually
between ages 8 and 14, the pituitary gland, located just beneath the brain, secretes
two hormones (luteinizing hormone, or LH; and follicle-stimulating hormone, or FSH)
that work together to stimulate the ovaries to make estradiol. Increased estradiol
production is largely responsible for breast development, genital growth, and changes
in the distribution of body fat in pubescent girls.
Because human sex hormones work so closely with one another, doctors often perform
the estradiol test with tests for LH, FSH, testosterone (the male sex hormone —
but teen and adult females produce some, too), and progesterone (the hormone that
prepares the body for pregnancy). Taken together, the results can often provide a
more complete picture of a person's sexual maturation status and help doctors diagnose
diseases causing sex hormone imbalances.
Why It's Done
Doctors may order an estradiol test if a 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.
Estradiol levels also give important information on the functioning of the ovaries.
This can help doctors evaluate menstrual problems, including abnormal bleeding or
missing periods. The test may also be used in boys or girls to check for damage or
disease of the testes, ovaries, or adrenal glands.
Testing estradiol levels also can be used to monitor the progression of a pregnancy,
fertility treatments, or to evaluate menopause symptoms.
Preparation
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 your child
and the technician who will be drawing the blood.
