Follicle Stimulating Hormone (FSH)
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-ovarian" 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.
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