The impact of bone loss in women with endometriosis

Short- and long-term impact of gonadotropin-releasing hormone analogue treatment on bone loss and fracture

Gonadotropin-releasing hormone analogues (GnRH-a) are commonly utilized in moderate to severe endometriosis to induce atrophy of endometriotic lesions. Unfortunately, cessation of therapy can lead to recurrence of symptoms. Therefore, long term therapy is sometimes necessary. GnRH analogues cause an immediate decrease in bone mineral density which usually recovers after cessation of its use. However, this recovery in bone mineral density may not always occur after long term use. In order to prevent the deleterious effects on bone, add-back therapy is used frequently. This review will explore the impact of GnRH analogues on both bone loss and fracture risk as well as describe different add-back regimens.

Long-term fracture risk among women with proven endometriosis

OBJECTIVE

To determine whether women with pelvic endometriosis are at increased fracture risk.

DESIGN

Historical cohort study.

SETTING

Population-based investigation using the data resources of the Rochester Epidemiology Project.

PATIENT(S)

From Olmsted County, Minnesota, 987 women with endometriosis that was first surgically visualized or histologically proven in 1970-1989.

INTERVENTION(S)

None, observational study.

MAIN OUTCOME MEASURE(S)

Follow-up for fractures through complete inpatient and outpatient community medical records.

RESULT(S)

In 17,408 person-years of follow-up, 256 women experienced 449 different fractures. The cumulative incidence after 20 years (30.8%) was not elevated relative to that expected (30.6%). The independent predictors of any fracture included age (hazard ratio [HR] per 10 years: 1.61; 95% confidence interval [CI] 1.42-1.84]), corticosteroid use (HR: 2.78; 95% CI 1.48-5.24), prior hip, spine, or forearm fracture (HR: 1.82; 95% CI 1.10-3.02), and use of the selective estrogen receptor modulators, tamoxifen or raloxifene (HR: 4.34; 95% CI 2.14-8.81); physical activity was protective (HR: 0.40; 95% CI 0.18-0.88). There was no significant influence on fracture risk of surgery or other medical treatments for endometriosis.

CONCLUSION(S)

Despite reported adverse effects of treatment on bone density, there was no overall increase in long-term fracture risk in this unselected cohort of women with proven endometriosis.

Excretion of urinary N-telopeptides reflects changes in bone turnover during ovarian suppression and indicates individually variable estradiol threshold for bone loss

OBJECTIVE

To evaluate the effectiveness of N-telopeptides and E2 in monitoring bone turnover during GnRH agonist- (GnRH-a) or danazol-induced hypoestrogenism.

DESIGN

Comparative, nonrandomized prospective study.

SETTING

Institute for the Study and Treatment of Endometriosis.

PATIENT(S)

Premenopausal women undergoing ovarian suppression with GnRH-a (n = 16) or danazol (n = 9).

INTERVENTION(S)

Serum and urine samples were collected and bone mineral density was measured before, during, and after treatment.

MAIN OUTCOME MEASURE(S)

N-telopeptide excretion, serum E2, and bone mineral density at L1 to L4 and femoral neck.

RESULT(S)

During treatment in the GnRH-a group, mean E2 levels were 53% below and N-telopeptides were 38% above the mean baseline. At 1 month post-treatment, L1 to L4 bone mineral density decreased by 3.85%. In the danazol group, E2, N-telopeptides and L1 to L4 bone mineral density changed nonsignificantly in the opposite direction with the mean 1.25% increase in L1 to L4 at 1 month post-treatment. In combined groups, L1 to L4 bone mineral density better correlated with other measures than femoral neck bone mineral density. N-telopeptide excretion was more predictive of L1 to L4 change, with correlation the highest between N-telopeptides at month 4 and bone mineral density at month 1 afterward, while E2 appeared more predictive of the less reliable femoral neck bone mineral density. Individual exceptions to the model of an E2 threshold for bone loss were observed. Also noted were high correlation between on-therapy levels of E2 and N-telopeptides, as well as the presence of a 1-month time lag between E2 and N-telopeptide changes.

CONCLUSION(S)

Bone density decreases during GnRH-a and may slightly increase during danazol treatment. However, E2 threshold for bone loss varies individually. N-telopeptides predict changes in bone mineral density at L1 to L4 better than E2.