Follicle Stimulating Hormone (FSH), Gonal-F, Follistim, Repronex, Bravelle, Menopur

Follicle stimulating hormone (FSH) is produced by the pituitary gland under the influence of gonadotropin releasing hormone (GnRH), which is secreted from the hypothalamus. FSH stimulates the recruitment and development of follicles each of which contains an egg. When FSH is given by injection it causes an increase in the number of follicles.

Pergonal was the first FSH containing product introduced in the United States and is no longer available. Pergonal was "human derived" meaning it was a natural product extracted from the urine of post menopausal women. FSH levels are naturally high in these women because the ovaries have ceased functioning. Pergonal was a mixture of equal amounts of FSH and LH. It contained some impurities that were chiefly proteins contained in the urinary preparation that could not be removed. These proteins were responsible for skin reactions in some and mandated the medication be administered intramuscularly.

Newer products such as Follistim and Gonal-F are manufactured using genetic recombinant mammalian cell technology. The engineered mammalian cells produce FSH that is identical to that made in the body. These products do not contain the impurities seen in other "human derived products".

There is debate about the need for luteinizing hormone (LH) in FSH products. Some physicians believe that a small amount of LH causes a "better" stimulation and helps endometrial development by raising estrogen levels and others prefer the pure products. The product selected is based upon factors such as the cause (s) of infertility, female age, stimulation history, and other factors.

Bravelle, Repronex, and Menopur are forms of human derived FSH manufactured by Ferring laboratories. Repronex is similar to Pergonal having significant amounts of LH whereas Bravelle has less than 2% LH activity. One advantage of these products is they are less expensive. Both are more pure than old Pergonal, and may therefore be administered subcutaneously. Menopur, a newer Ferring product, is "highly purified" and contains equal amounts of FSH ( 75 units ) and LH ( 75 units ). It is the first gonadotropin product approved by the FDA on the basis of pregnancy rates.

All of today's FSH products are approved for subcutaneous administration due to their increased purity. They should ideally be administered by a reproductive endocrinologist/fertility specialist as they can produce serious side effects. Patients must be monitored carefully to prevent ovarian hyperstimulation syndrome, a relatively rare, but serious side effect that can lead to ovarian enlargement, vascular dehydration, ascites (collection of fluid in the abdomen), and clotting abnormalities. The IVF stimulation cycle must also be carefully "adjusted" to reduce the risk of high order (>3) multiple births.

FSH products are prescribed for assisted reproductive technology cycles (IVF) and in stimulated intrauterine insemination (IUI). More eggs are needed for an IVF cycle than in an ovulation induction cycle.

Patients undergoing FSH stimulation may receive Lupron, Cetrotide, or Ganirelix. These products cause down regulation of the "hormone system" blocking the production of FSH and LH and spontaneous ovulation.

In a natural cycle, the hypothalamus initiates ovulation when the eggs mature by releasing a surge of luteinizing hormone (LH). This "surge" cannot occur while patients are on Lupron or Ganirelix. If ovulation occurred prior to egg retrieval, the stimulation cycle would be "lost".

Once the follicles mature, an injection of human chorionic gonadotropin (hCG) is administered to cause oocyte maturation and eventual ovulation. The body reacts to hCG as it does to the LH surge. Retrieval is usually scheduled 34 to 36 hours after the hCG injection.

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