Objective: To examine the utility of a low-dose estrogen and pulsed progestogen hormone replacement therapy (HRT) regimen for add-back during long-term gonadotropin-releasing hormone-agonist (GnRH-agonist) therapy.
Design: A pilot clinical trial conducted at a tertiary referral, academic, reproductive sciences center. The study included 15 patients with endometriosis and 5 patients with severe premenstrual syndrome (PMS). Patients with endometriosis received leuprolide acetate depot 3.75 mg IM monthly until their symptoms had resolved (2-3 months), at which time HRT was initiated along with the GnRH-agonist. Patients with severe PMS received the same treatment with the addition of HRT after 1 month. The HRT regimen consisted of 1 mg oral micronized estradiol daily and 0.35 mg norethindrone daily for 2 days alternating with 2 days without norethindrone. The main outcome measure included bone density assessment in the lumbar spine and femoral neck by dual-energy x-ray absorptiometry at 6- to 12-month intervals. The mean follow-up duration +/- SD while on GnRH-agonist treatment was 31.2 +/- 17 months (for endometriosis patients) and 37.7 +/- 8.4 months (for patients with severe PMS).
Results: Bone mineral density was stable after initiation of HRT for the entire follow-up period. No patient had return of pelvic pain or resumption of mood swings after HRT add-back. After the first 3 months of HRT, all women remained amenorrheic.
Conclusions: Long-term GnRH-agonist down-regulation is safe and effective when combined with HRT add-back. Furthermore, on the basis of this small study, the low-dose pulsed progestogen, continuous estrogen HRT regimen seems to be safe for use as add-back therapy in terms of bone health.