••• Chapter 56^ GnRH and GnRH Analogs^563
❍ When do desensitization and downregulation occur?
1 to 3 weeks after initiation of treatment.
❍ When is GnRH agonist therapy initiated to avoid a flare effect?
Midluteal phase.
❍ Will a patient who has started a GnRH agonist in the midluteal phase (approximately day 21) get her menses?
Yes. Ovulation has occurred and therefore withdrawal from progesterone will result in menses. Thereafter,
ovulation (and menses) will likely be suppressed.
❍ How can GnRH therapy be monitored?
The patient may be seen monthly. Check baseline E2, FSH, and progesterone. Recheck serum E2 after 2 months
of therapy. Repeat bone density if treatment ≥6 months. Appropriate testing for specific sex steroid-dependent
diseases after 3 months of therapy.
❍ When does the GnRH therapy become effective in downregulating estradiol levels?
4 to 6 weeks. Patient should be amenorrheic by that time.
❍ What are the adverse effects of GnRH?
Hot flashes: >75%.
Irregular (light) vaginal bleeding: 30%.
Headache, mood changes, vaginal dryness, and arthralgias/myalgias: 5% to 15%.
Allergic reaction: <10%.
Bone loss: long term.
❍ At what estradiol level is suppression with GnRH therapy adequate?
<30 pg/mL.
❍ True or False: GnRH agonist treatment can delay the diagnosis of leiomyosarcoma.
True. However, its incidence is extremely low, especially in premenopausal women.
❍ What percentage of women going for myomectomy will end up having hysterectomy?
10% to 30%.
❍ What is the usefulness of GnRH therapy in fibroids?
Reduction in size of the fibroids and improvement in bleeding symptoms by 6 to 8 weeks of therapy. It also
increases the hemoglobin and hematocrit concentration.
❍ Which hormones are the endometrium and fibroid dependent for growth?
Estrogen (and perhaps progesterone for fibroids).
❍ What is the change in mean uterine volume seen with GnRH agonist treatment?
30% to 64% decrease in mean uterine size after 3 to 6 months of treatment.