ESPE Abstracts

Background: Adult subjects with Prader-Willi Syndrome (PWS) have low Bone Mineral Density (BMD) and are at risk of osteoporosis. Several observations suggest that peak bone mass is usually achieved by late adolescence, in the presence of adequate gonadal hormone concentrations. Consequently, the altered bone characteristics of PWS patients may be related to inadequate sex steroid levels during pubertal development.

Aim: To investigate BMD in PWS females during the transition phase.

Methods: Thirty-two females with genetically confirmed PWS, aged 22.1±0.4 year (mean+SE) (range 17.9–25.0 year), were studied. Eleven subjects were undergoing sex steroids therapy (Group A), while the remaining 21 individuals were naïve to substitutive treatment (Group B). Twenty subjects had undergone GH treatment during childhood. In all patients dual-energy X-ray absorptiometry (DXA) (Lunar Prodigy) was used to measure BMD in the lumbar spine L1-L4 (gr/cm²), BMD T-score, and BMD Z-score.

Results: Four PWS had osteoporosis (T-score <−2.5: 12.50%), 14 had osteopenia (T-score from −1.0 to −2.5: 43.75%) and 14 had normal BMD (43.75%). Three subjects out of 11 of Group A had osteopenia (27.3%), while the remaining 8/11 showed normal BMD (72.7%). Four PWS out of 21 of Group B had osteoporosis (19%), 11/21 had osteopenia (52.4%), and 6/21 had normal BMD (28.6%). Mean lumbar BMD, BMD T-score and BMD Z-score were higher in Group A in comparison to Group B (BMD: 1.108±0.02 g/cm² vs. 0.947±0.03 g/cm²: P=0.006; T-score: −0.69±0.17 versus −1.51±0.26: P=0.04; Z-score: −0.66±0.24 versus −1.3±0.28: P=0.9). Previously GH-treated patients had higher BMD T-score and BMD Z-score in respect to subjects naïve to GH treatment (−0.91±0.22 vs. −1.72±0.32: P=0.04 and −0.71±0.25 vs −1.69±0.32: P=0.02).

Conclusions: We conclude that (1) delayed timing of sex steroids therapy should be avoided in PWS females, and (2) GH therapy during childhood seems to exert positive effects on BMD during the transition phase.