Reduction of bone mineral density by gonadotropin-releasing hormone agonist, nafarelin, is not completely reversible at 6 months after the cessation of administration.

STUDY OBJECTIVE

To determine the reversibility of bone mineral density after the cessation of GnRH agonist treatment for endometriosis.

DESIGN

Longitudinal trial with 6-month treatment period and 6-month follow-up.

PATIENTS

28 Japanese premenopausal women with endometriosis.

INTERVENTIONS

Daily dose of 400 micrograms nafarelin was administered for 6 months.

MEASUREMENT AND MAIN RESULTS

The spine bone mineral density was measured by dual energy X-ray absorptiometry, and blood and urinary bone metabolic parameters were analyzed. The decrease of lumbar bone mineral density, which took place during treatment, continued during the first 3 months after the cessation of treatment and did not return to the initial baseline level even at 6 months after the withdrawal of treatment. The biochemical parameters, which showed a state of enhanced bone turnover during nafarelin treatment, almost returned to the pretreatment level 6 months after the termination of treatment.

CONCLUSION

These results indicate that relatively long period of bone metabolic change might be required to alter the actual bone mineral density after GnRH analog administration.