Is it possible to prevent bone loss in young women treated with luteinizing hormone-releasing hormone agonists?

Recent studies have shown that treatment with the LHRH agonist nafarelin gives symptomatic and objective relief to women with endometriosis. Such a treatment, however, results in increased bone turnover and loss of bone mass. In the present study 17 women with endometriosis were treated with 400 mg nafarelin combined with 1.2 mg norethisterone (NET) for 6 months, followed by 6 months with only 1.2 mg NET. The data were compared to data from a previously published study of 9 women treated for 6 months with 400 mg nafarelin alone, followed by 6 months without treatment. In the group treated with nafarelin plus NET the biochemical parameter of bone resorption (fasting urinary hydroxyproline) remained virtually unchanged, compared to a highly significant increase in the nafarelin-treated group. Estimates of bone formation (serum alkaline phosphatase and plasma bone Gla protein) increased in the nafarelin plus NET group, but to only a minor extent compared to those in the nafarelin group. In addition, bone mineral in the forearm, the spine, and the total skeleton remained virtually unchanged in the group treated with nafarelin plus NET, compared to the bone loss of 2-6%/6 months in the nafarelin group. We conclude that addition of NET to nafarelin treatment of endometriosis seems to have a bone-sparing effect.