What Is a Luteinizing
Hormone Response to Gonadotropin Releasing Hormone Test?
Both luteinizing hormone (LH) and
gonadotropin-releasing hormone (GnRH) are important in male and female
reproduction. Their interaction is a vital part of the menstrual cycle and
conception in women. They’re also important to the production of sperm cells in
An “LH response to GnRH test” is a
blood test that tells your doctor whether or not your pituitary gland is
functioning correctly when GnRH binds to its receptors. If it’s working
correctly, it should cause LH to be released into the bloodstream. If it's not
working correctly, the test can help doctors figure out underlying reasons for
certain symptoms, such as low hormone levels.
A test of the response of LH to GnRH
can help doctors determine underlying reasons for certain symptoms in their
patients, such as low hormone levels.
What Are Luteinizing and Gonadotropin-Releasing Hormones?
GnRH is a hormone produced in the
hypothalamus region of the brain. GnRH moves through the bloodstream to the
pituitary gland. There, it binds to certain receptors. Those receptors signal
the pituitary gland to create two more hormones: LH and follicle-stimulating
In women, FSH goes on to stimulate the
growth of eggs in the ovaries. This leads to the production of estrogen,
another hormone, which sends a signal back to the pituitary gland to slow the
releasing of FSH and to make more LH. The change leads to ovulation and a drop
in both LH and FSH.
After ovulation, the empty follicle in
the ovary begins producing yet another hormone, progesterone, which is needed
to maintain a pregnancy. If ovulation does not lead to pregnancy, the cycle
goes back to the beginning.
In men, GnRH stimulates the release of
LH from the pituitary gland. LH then binds to receptor cells in the testicles
to begin the production of sperm cells.
What Are the Reasons for
Requesting an LH Response to GnRH Test?
There are two main reasons why your
doctor may order an LH response to GnRH test: to evaluate hormone levels and to
confirm primary or secondary hypogonadism.
Hypogonadism occurs when the sex
glands in either men (testes) or women (ovaries) produce little or no hormones.
It can be caused by genetic disorders like Turner, Klinefelter, and Kallmann
syndromes. It can also be caused by tumors. When hypogonadism centers on the
testes or ovaries, it’s called primary hypogonadism. When it centers in the
pituitary gland and hypothalamus areas of the brain, it’s called central or
To treat hypogonadism, your doctor
needs to know if it’s primary or secondary. The LH response to GnRH test can
indicate where the problem occurs in your body.
Your doctor may also order an LH
response to GnRH test to check the level of certain hormones in your body. It
can give a doctor an idea of testosterone levels in male patients and estradiol
levels (an important form of estrogen) in female patients.
How Is the Test
To perform an LH response to GnRH
test, your doctor needs to take a sample of your blood. Then they’ll give you a
shot of GnRH. Over a period of time, typically 20 minutes and 60 minutes after
the injection, additional blood samples will be drawn so the luteinizing
hormone (LH) can be measured.
You’ll do the test in a lab in your
doctor’s building or right in the office. A nurse or medical assistant will
take your blood by inserting a needle into a vein in the inside of your arm. A
tube connected to that needle will collect a small amount of blood.
What Are the Risks
Associated with an LH Response to GnRH Test?
There are very few risks associated
with having blood drawn. You may have a small amount of bruising where the
needle was inserted. You can minimize it by putting pressure on the wound after
the nurse removes the needle. In rare cases, you may experience phlebitis, an
inflammation of your vein. It’s not a serious problem. You’ll just need to
apply a warm compress to the needle site throughout the day.
How Should I Prepare for an
LH Response to GnRH Test?
Your doctor will tell you what to do
before having your blood drawn for an LH response to GnRH test. You should tell
your doctor if you have any bleeding disorders. You may need to stop taking
certain medications before the test, such as birth control and any other hormone
pills. They may interfere with your results. Your doctor will likely also ask
that you don't eat or drink anything during the eight hours leading up to the
Interpreting the Results of
Interpreting the LH response to GnRH
test is very complicated. It considers gender, age, and weight. The results of
the tests compare LH levels and FSH (follicle-stimulating hormone) levels over
When the LH response is higher than
normal, it may indicate primary hypogonadism or a problem with the ovaries or
testes. When the response is too low, it may indicate secondary hypogonadism or
an issue with the pituitary gland and hypothalamus.
Other reasons for abnormal results
- pituitary tumors
- Kallmann syndrome
- irregular or absent periods
- hyperprolactinemia (having an excess of
prolactin, the hormone that produces breast milk in women)
Your doctor will explain the results
of your test to you. The values of the test can vary, depending on the
laboratory that does the work.