Effects of a gonadotropin-releasing hormone agonist on the calcium-parathyroid axis and bone turnover in women with endometriosis

OBJECTIVE: Our purpose was to investigate the effects of nafarelin on bone turnover and mass (bone mineral desntiy, in grams per square centimeter) in women with endometriosis. STUDY DESIGN: We monitored 22 young women with endometriosis during and 6 months after 6 months of nafarelin treatment. We compared the bone mineral density status of these women with that of healthy controls undergoing sequential bone mineral density measurement. RESULTS: Subjects had a 2.2% loss in L2–4 bone mineral density by 6 months, increasing 3 months later to 3% and returning toward baseline by 6 months after treatment. Radius bone mineral density did not change in the treatment group. Bone mineral density did not change in controls. Serum and urinary calcium levels rose during treatment. Hydroxyproline excretion increased and remained elevated 6 months after treatment. A rise in serum osteocalcin persisted 3 months after therapy but normalized by 6 months. CONCLUSIONS: Bone mineral density deficits with nafarelin are reversible. Increased bone turnover persists 6 months beyond treatment, demonstrating the need for careful monitoring of women receiving prolonged or repeated treatment.