ESPE Abstracts

Context: In children with Prader-Willi syndrome (PWS), the benefits of growth hormone (GH) treatment are well established. Currently, when young adults with PWS have attained adult height (AH), they have to stop GH treatment. Several one year studies have shown that GH treatment is also beneficial for adults with PWS, improving body composition. However, little is known about the longer-term effects.

Objective: To investigate the effect of either continuation of GH for 2 years after AH attainment or restart of GH for 2 years after cessation for a median period of 1 year on body composition

Design: Open-label, prospective study in 48 young adults with PWS

Setting: Dutch PWS Reference Center

Main outcome measures: Fat mass percentage (FM%) SDS and Lean body mass (LBM) SDS, measured by DXA

Results: In the 22 adults who continued GH after AH attainment, estimated mean (95% CI) FM% SDS did not change during 2 years of GH treatment (2.2 (1.9 to 2.4) SDS at baseline vs. 2.2 (2.0 to 2.4) SDS after 2 years, P=0.42), neither did LBM SDS (-2.0 (-2.6 to -1.5) SDS vs. -2.0 (-2.5 to -1.5) SDS, P=0.94). In the 26 adults who restarted GH after they had stopped GH for a median duration of 1 year, FM% SDS decreased significantly during 2 years of GH, from 2.2 (2.0 to 2.4) SDS to 1.9 (1.7 to 2.1) SDS, P<0.001, while total body LBM SDS increased significantly from -2.3 (-2.7 to -2.0) SDS to -1.9 (-2.2 to -1.5) SDS, P<0.001. Estimated mean fasting glucose increased from 4.2 mmol/l at baseline to 4.8 mmol/l after 2 years of GH treatment (P=0.004), and insulin from 42.5 pmol/l to 69.5 pmol/l (P=0.001), but both remained within normal limits. None of the patients developed type 2 diabetes mellitus. Systolic and diastolic blood pressure did not change during 2 years of GH and were within the normal range in all patients.There were no GH-related adverse events during the study.

Conclusions: Continuation of GH treatment for two years after attainment of AH maintains the positive effects on body composition attained during childhood, while restart of GH after discontinuation for 1 year improves body composition. Thus, adults with PWS benefit from longer-term GH treatment, without major side effects or safety concerns.