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FSH is produced
by the pituitary gland under the influence of GnRH,
which is released by the hypothalamus. In a normal cycle,
levels of FSH vary in relationship to hormones such
as estrogen.
When FSH is given by injection,
it directly stimulates the recruitment and development
of follicles in contrast to Clomid,
which works at the hypothalamus. Numerous eggs are needed
in IVF
cycles as some are immature and can not be fertilized.
As patients undergo ovulation induction with FSH, they
are carefully monitored by estradiol measurements, ultrasound
to visualize the ovaries and follicles, and physical
examination. Products such as Lupron,
Cetrotide, or Ganirelix Acetate are given to control the time
of ovulation.
FSH should only be administered
by an fertility
specialist / reproductive endocrinologist thoroughly
trained in its use. Patients must be monitored and dosages
adjusted to avoid potentially serious side effects such
as ovarian hyperstimulation. Most high order multiple
births reported by the media are due to FSH stimulated
intrauterine insemination IUI
cycles that were not managed by a specialist.
FSH containing products were first
introduced in the United States by Serono Laboratories
under the trade name Pergonal. These first products
were "natural" in that they were derived and
purified from the urine of post menopausal women. Because
they were human derived they also contained impurities,
notably luteinizing hormone (LH). They also had to be
administered by intramuscular injection, which is painful
and inconvenient.
More recent products include Gonal-F,
and Follistim, which are produced using genetic recombinant
technology. These FSH products are pure and can be given
subcutaneously. Bravelle and Menopur are highly purified
"human derived" products that can also be
given subcutaneously.
There is debate among physicians
and embryologists as to the need for LH in FSH stimulated
cycles. All physicians administer these products using
individualized protocols for each patient. Many physicians
believe that a minute quantity of LH causes a "better
stimulation" in some patient groups. Mixed protocols
using Follistim (FSH) and Bravelle, Menopur or Repronex
are often used.
Serono recently released Luveris
(recombinant LH) for use in patients that are hypogonadotropic
(have very low levels of gonadotropins).
Read
an Article on Fertility Drugs- "Demystifying Fertility
Drugs"
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