Dr Kaylen Silverberg - How are Gonadotropins used in infertility therapy?
Injectable Fertility Medications: Gonadotropins for Ovarian Stimulation
Gondadotropin Stimulation
Gonadotropins are powerful
medications that can be administered to stimulate
follicular development within the ovaries. There
are two different types of gonadotropins, follicle
stimulating hormone (FSH) and luteinizing hormone (LH).
These hormones are naturally produced by the
pituitary gland, a small structure that resides
behind your nose at the base of the brain. Under
normal circumstances, the pituitary gland makes FSH
and LH in a specific sequence and in a specific
amount that causes only one follicle to ultimately
grow and ovulate in any given month. When these
medications are given in pharmacologic doses,
several follicles can develop and subsequently
ovulate. These medications have been combined with
intrauterine insemination (IUI) to produce very high
pregnancy rates. As a result, this treatment has
become a mainstay of therapy for a variety of
different conditions causing infertility.
Initially, gonadotropin therapy
combined with IUI was used as a treatment for
patients who did not respond to clomiphene citrate.
As pregnancy rates have increased, this therapy is
now frequently recommended for a variety of other
conditions as well, including treated endometriosis,
male factor, cervical factor, and unexplained
infertility.
In a typical gonadotropin
cycle, we will schedule you to come in to the office
for a baseline ultrasound examination on the first,
second, or third day of your menstrual cycle. If
the ultrasound confirms that there are no cysts
within your ovaries, we will ask you to begin taking
a single injection of gonadotropin daily. As these
medications are powerful, we will monitor you
closely with a combination of vaginal
ultrasonography and blood estrogen levels every two
to three days during the follicular maturation
process. When ultrasound demonstrates that your
largest follicles are mature (typically 19 to 20 mm
in average diameter), a single injection of hCG or
Ovidrel will be administered. This injection
triggers the egg to actually come out of the
follicle (“ovulation”). Intrauterine inseminations
are performed on each of the next two days following
the Ovidrel injection.
The side effects of
gonadotropin therapy include bloating, cyst
development, multiple pregnancy, and a very rare
condition called ovarian
hyperstimulation syndrome. While the typical
chance for pregnancy is based on the patient's age,
a woman 35 years of age or younger should expect a
pregnancy rate of 20-25% per cycle of gonadotropin/IUI
therapy.
There are several different
classes of gonadotropins. Some are made from a recombinant DNA technology
while others come from human urine. At TFC, we
prefer recombinant DNA produced gonadotropins (Gonal- F and Follistim®),
as these products are over 99% pure. You can inject
yourself subcutaneously (just underneath the skin)
with a small needle, as these shots are relatively
painless. The other class of drugs, urinary
products such as Menopur®
and Repronex®,
are also effective at producing follicular
development, ovulation, and pregnancy. They are,
however, obtained from purified urine produced by
postmenopausal women. Therefore, there are
theoretic concerns about their safety, as they do
contain small amounts of protein (albeit sterilized
protein) from other humans.
In summary, gonadotropin
therapy combined with IUI offers many couples an
outstanding chance for pregnancy at a fraction of
the cost of a cycle of in vitro fertilization. Due
to the risks of multiple pregnancy and
hyperstimulation, we monitor our patients very
closely, both to maximize the chance for pregnancy
and to minimize the likelihood of side effects.
