Endometriosis and Fertility Resource Page

How Does GnRH Agonist Work?
GnRH agonist (e.g. Zoladex and Lupron) interrupts normal menstruation and the production of estrogen. Normally, gonadotropin-releasing hormone (GnRH), a hormone produced in the brain, acts on the pituitary gland (also in the brain) to stimulate the production of two other hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH then stimulate the ovaries to release eggs (a process called ovulation) and produce female hormones, including estrogen. In turn, ovarian function controls the timing and duration of menstruation. GnRH agonist interrupts the signals from the brain to the ovaries. As a result, ovulation does not occur, and the ovaries produce very little estrogen. GnRH agonist produces a state of pseudo-menopause – that is, it “tricks” the body into thinking it is in menopause. With menopause, menstruation ceases and estrogen production falls to very low levels. The same events typically occur with administration of GnRH agonist.

When Is GnRH Agonist Used?
GnRH agonist can be used to help treat a number of gynecological conditions, including:

• Endometriosis
• Uterine Fibroids
• Certain types of abnormal uterine bleeding
• Certain pelvic pain syndromes, such as pelvic congestion syndrome

You should talk with your doctor to determine whether GnRH agonist therapy might be appropriate for your condition.

What Is The Treatment Regimen?
GnRH agonist is administered every 28 days for the duration of the treatment period. Depending upon your condition, your doctor may recommend a treatment period of between two and six months.

GnRH agonist typically works for about six weeks after it is administered. After this time, the effects of GnRH agonist begin to wear off. Normal menstrual function typically resumes about ten weeks after the last dose of GnRH agonist.

What Are The Benefits Of GnRH Agonist Therapy?
GnRH agonist therapy alone seldom cures a gynecological condition. Typically, GnRH agonist therapy is given:

• To get a condition (e.g. endometriosis) under good control, which makes it more likely that you will be successfully transitioned to another long-term medical treatment after your course of GnRH agonist.
• In preparation for certain surgeries (e.g. for fibroids) to make it more likely that the surgery will successfully treat your problem, to reduce blood loss during surgery, and/or to reduce the size of the uterus.

What Are The Side-Effects?
Most women tolerate GnRH agonist therapy well. Side-effects of GnRH agonist therapy may include:

• Menopausal symptoms such as hot flashes, night sweats, and vaginal dryness. These symptoms occur in most women using GnRH agonist, but are seldom severe.
• Mood changes such as irritability and low energy. These symptoms occur in many women using GnRH agonist, but are seldom severe. Occasionally, GnRH agonist may cause depression, particularly in women who have a history of prior depression.
• Decreased libido / sex drive (fairly common)
• Headaches (somewhat common)
• Irregular bleeding occurs in some women. In order to minimize problems with abnormal bleeding, the first dose of GnRH agonist is typically given about one week before the expected onset of the menses. If irregular bleeding occurs, it typically goes away after the second dose.
• Osteoporosis. GnRH agonist therapy causes some thinning of the bones. For this reason, the treatment period with GnRH agonist is typically limited to six months. GnRH agonist should not cause osteoporosis in women that otherwise have healthy bones. You can counter-balance the bone-thinning effects of GnRH agonist by taking calcium with Vitamin D (at least 500 mg of calcium two times a day), by performing weight-bearing exercise, and by avoiding smoking and excessive alcohol intake.

Who Should Not Use GnRH Agonist?
You should not use GnRH agonist if you:

• Are pregnant, might be pregnant, or are trying to become pregnant
• Are breastfeeding
• Have undiagnosed vaginal bleeding
• Have experienced an allergic reaction to GnRH agonist in the past
• Have been diagnosed with osteoporosis. If you have risk factors for osteoporosis (e.g. a family history of osteoporosis, or a personal history of bone fractures), bone density testing might be advisable before GnRH agonist therapy is initiated.
• Have a history of significant depression, suicidal thoughts, or prior attempted suicide.

(Source: Mather - McClellan Women’s Health)

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