Evidence that the loss of bone mass induced by GnRH agonists is not totally recovered.

There is disagreement as to whether the loss of bone mass induced by GnRH agonists is reversible. In part, the differences of opinion might be attributed to the fact that the influence of weight and seasonal changes on bone mass is often overlooked. Taking into consideration weight and seasonal changes in bone mass, total (TBBMC) and regional body bone mineral content were measured in 38 women treated with GnRH agonists for 6 months for endometriosis or leiomyomata. Measurements were made at the onset of treatment, at 6 months of treatment and at 6 months after finishing treatment. TBBMC was corrected for body weight. Body weight had increased significantly at 6 months of treatment (P = 0.0175). Regional bone mineral content showed the following: limbs, no changes; head, significantly lower at 12 months than at baseline (P = 0.0036) and at 6 months (P = 0.0343) of therapy; trunk, significantly lower at 6 months (P = 0.0002) compared to baseline, but the values at 1 year were not significantly different from either the baseline or the 6-month values; pelvis, the same pattern of change as in the trunk (P = 0.0349). TBBMC was significantly lower at 6 months of treatment (P < 0.0001) and at 1 year (P = 0.0162). TBBMC adjusted for weight experienced the same changes as unadjusted bone mineral content (P < 0.0001 and P < 0.0009 at 6 months and 1 year, respectively). Our findings indicate that the bone mass lost with GnRH treatment had not been restored 6 months after discontinuing treatment.