Follicle
stimulating hormone (FSH) is naturally produced
by the pituitary gland and stimulates the recruitment
and development of the ovarian follicles located on
the ovaries, each of which contains an egg. FSH is also
referred to as a pituitary gonadotropin.
The
production of FSH and other
reproductive hormones is controlled by the complex
interaction of several hormones in a biologic feedback
system known as the "hypothalamic-pituitary-adrenal"
axis. The hypothalamus is the "master gland"
in control of regulating these processes.
The
first FSH commercial gonadotropin in the United States,
Pergonal, was released by Serono Laboratories. Pergonal
is derived from the urine of post-menopausal women and
purified for injection. FSH levels are higher in women
who are menopausal making their urine a good source
for extraction. Pergonal also contains leutinizing hormone
(LH) which produces many effects including higher estrogen
levels.
Newer
FSH products include Gonal-F and Follistim which are
obtained from mammalian cell cultures through recombinant
DNA technology. These products are pure and do not contain
the "contaminants" seen in Pergonal. Pergonal
has to be administered by intramuscular injection while
the newer medications are given subcutaneously with
much less discomfort Both human and genetically derived
products are difficult to obtain and manufacture and
are therefore expensive.
Opinions
differ as to the need for additional LH in FSH
stimulated cycles. Some physicians prefer protocols
that combine products containing LH with Gonal-F (pure
FSH). When a patient is "down regulated" with Lupron, or
especially Antagon or Cetrotide, natural levels of LH
are reduced to very low levels and some externally administered
LH is believed by many to be beneficial. Egg
quality is difficult (at best) to judge but some embryologists
believe pure FSH cycles produce "better quality"
eggs.
In
procedures such as in vitro fertilization,
FSH is administered by injection to cause the development
of numerous eggs which can be retrieved and fertilized.
When FSH is used in stimulated intrauterine insemination
cycles, there is less control over how many eggs are
ovulated thus increasing the chances of multiple births.
Most cases of quadruplets, or more, result from stimulated
IUI cycles. Patients must be closely monitored by a reproductive endocrinologist to minimize the risk of multiple births.
FSH
should only be administered by a reproductive endocrinologist thoroughly trained in its use. Serious side effects
can occur and patients must be closely monitored with
estradiol hormone level measurements and ultrasound.
Hyperstimulation is a very serious, but rare, complication
that can result in stroke and other like threatening
events. Side effects are minimized when these products
are monitored by specialists with extensive clinical
training in their use.
|
