GnRH agonists are given as an injectable medication, which offer a high amenorrhea rate (73-97%). (29) It has been proven to be superior to DMPA in preventing moderate to severe bleeding in young women undergoing myelosuppressive chemotherapy with subsequent severe thrombocytopenia. (30) It can be given intravenous (IV), subcutaneous (SC) or intramuscular (IM) with a frequency ranging from every day to every 8 to 12 weeks according to the route of administration. Typically, leuprolide-depot is chosen and given every 8 to 12 weeks IM. Alternatively if the patient is thrombocytopenic, leuprolide IV can be given daily until platelet counts are safe for an IM injection to be given.
Breakthrough bleeding for the first 2 to 3 weeks after initial injection is common and should be planned for within the course of disease or therapy. Possible side effects are hot flashes, insomnia, joint pain, and weight gain and mood disturbance. The main risk of medication is a decrease in bone mineral density, as well as local contusion or hematoma from the injection itself. Patients should be offered immediate add back therapy to prevent vasomotor symptoms and negative impact on bone mineral density (BMD). Options of add back therapies include: norethindrone acetate 5 to 10 mg daily alone or very low dose estradiol with progestin. Norethindrone acetate is a progestin with estrogenic action, which has been shown as effective as low dose estradiol to prevent BMD decreases and vasomotor symptoms, without any thromboembolic risk. (31, 31)
Menstrual suppression using GnRH agonists should be given only for a limited time during chemotherapy treatment and/or during the timeframe that the patient is at risk for low blood count secondary to treatment or malignancy.