Decreased bone density in elderly men treated with the gonadotropin-releasing hormone agonist decapeptyl (D-Trp6-GnRH).

Administration of GnRH agonist analogs to women may result in a hypoestrogenic state and bone mass reduction. In the present study we examined bone mineral density (BMD) and parameters of mineral metabolism in elderly men with benign prostatic hyperplasia before and during a hypoandrogenic state induced by the long-acting GnRH agonist D-Trp6-LHRH (decapeptyl). Our results showed that decapeptyl treatment caused a significant decrease in serum testosterone concentrations in all patients and resulted in a significant decrease in individual vertebral BMD in 10 of 17 patients. A significant decrease in BMD was observed in 5 patients after 6 months of treatment. Another 5 patients showed a decreased BMD only after 12 months. The mean serum concentrations of osteocalcin, phosphorus, and alkaline phosphatase activity increased after 6-12 months of treatment with decapeptyl. Serum calcium, vitamin D metabolites, and PTH concentrations remained unchanged during treatment. Urinary calcium excretion was slightly, but not significantly, increased after 6 months of treatment. These results demonstrate that long-acting GnRH agonist treatment may cause high turnover accelerated bone loss in some men during the first year of GnRH agonist treatment, as has been previously shown in women.