Objective: Our purpose was to determine whether intermittent cyclic etidronate therapy blocks the decline in bone density associated with gonadotropin-releasing hormone agonist therapy.
Study design: Thirty-one premenopausal subjects who needed treatment with leuprolide (Lupron) 3.75 mg monthly for 6 months were randomized to etidronate or placebo. Bone turnover was assessed by measurement of serum calcium, phosphorus, alkaline phosphatase, and fasting urinary calcium/creatinine ratios. Bone density was measured by dual energy x-ray absorptiometry.
Results: Gonadotropin-releasing hormone treatment produced a significant decrease (4% to 10%) in bone density at the anteroposterior and lateral spine in placebo-treated patients (11). No significant change was demonstrated in etidronate-treated patients (15). Significant increases in serum calcium, phosphorus, alkaline phosphatase, and urinary calcium/creatinine ratios were noted in the placebo group. No significant change in these parameters were evident in the etidronate group.
Conclusion: Etidronate blocks bone mineral density changes associated with gonadotropin-releasing hormone agonist therapy and normalizes serum and urine indicators of bone turnover.