THE EFFECTS OF GONADOTROPIN-RELEASING-HORMONE AGONISTS ON ILIAC CRESTCANCELLOUS BONE-STRUCTURE IN WOMEN WITH ENDOMETRIOSIS

The administration of gonadotrophin-releasing hormone (GnRH) analogs t o premenopausal women causes hypoestrogenism and bone loss, but the ef fects on cancellous microstructure have not been determined, In this s tudy we have assessed bone structure in transiliac biopsies obtained f rom women before and after treatment for endometriosis with GnRH analo gs, Twenty-one premenopausal women were studied, paired biopsies being obtained in 13; five women received both GnRH analogs and Org OD 14 ( Tibolone, Livial), Comparison of pre- and post-treatment biopsies in w omen treated only with GnRH analogs showed a reduction in indices rela ted to connectivity (node-to-terminus ratio, node-to-loop strut length , p < 0.02) and increase in inversely related indices (terminus-to-ter minus and node-to-terminus strut length, p < 0.03), No significant cha nges were seen in any of the structural indices in women receiving bot h GnRH and Org OD 14 therapy, Activation frequency and bone formation rate at tissue level increased in women treated with GnRH agonists alo ne, although this change was not statistically significant, Our result s suggest that bone loss induced by GnRH analogs may be associated wit h adverse effects on cancellous microstructure which are unlikely to b e reversed following cessation of therapy, Concurrent treatment with O rg OD 14 appears to prevent these changes.