Growth hormone therapy improves exercise capacity in adult patients with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is associated with an inappropriate proportion of fat mass (FM) to non-FM compared to simple obesity. Altered body composition in PWS resembles that seen in subjects with GH deficiency, in which a reduction of lean body mass (LBM) is observed. The low LBM may contribute to the reduced motor skills seen in PWS patients.

The objective of the study was to investigate the effects of GH therapy on exercise capacity and body composition in a group of adult subjects with PWS.

Twelve PWS adults (7 males and 5 females, aged 26.4+/-4.4 yr, body mass index 44.3+/-4.6 kg/m2) participated in the study. Body composition analysis and exercise stress test were carried out throughout the 12 months GH therapy. Body composition was measured by Dual Energy X-ray Absorptiometry. Physical performance was evaluated using treadmill exercise test. Exercise intensity was expressed as metabolic equivalents (MET, 1 MET= 3.5 ml O2 kg(-1) min(-1)). Statistical analysis was performed by repeated-measures analysis of variance followed by post-hoc analysis with t test for paired data for comparisons among the different follow ups.

Compared to baseline GH therapy increased LBM at 6 (p<0.0001) and 12 months (p<0.005) (45.3+/-7.7 kg vs 48.6+/-6.7 kg vs 48.2+/-7.5 kg). FM% was significantly reduced both after 6 and 12 months (p<0.02) (56.1+/-4.8% vs 53.7+/-4.2% vs 53.3+/-4.8%). Attained MET were found to be improved by 16% after 6 months and by 19% after 12 months of GH (p<0.001), while the small further rise between 6 and 12 months was not significant.

Our findings seem to support the view that GH therapy has beneficial effects on physical activity and agility as well as on body composition of adult patients with PWS.