Growth hormone treatment for two years is safe and effective in adults with Prader-Willi syndrome

Prader-Willi syndrome (PWS) shares similarities with the growth hormone (GH) deficiency syndrome in regards to reduced lean body mass and increased fat mass and several short-term trials with GH treatment have demonstrated beneficial effects on body composition. The aim of the present study was to evaluate the effects and safety of two years of GH therapy in adults with PWS.

Forty-three adults (24 women) with genetically verified PWS were included. Blood samples, body composition as measured by computed tomography (CT) and dual-energy x-ray absorptiometry (DXA) were performed at baseline and during two years of continued GH treatment.

Thirty-nine patients completed treatment for two years. The GH dosage averaged 0.61 mg/day (range 0.2-1.6). Based upon CT, body composition improved at two years; thigh muscle volume increased 6.7 mL (3.7 to 9.7; P<0.001) whereas abdominal subcutaneous fat volume decreased by 53.3 mL (13.8 to 92.9; P=0.01). By DXA, lean body mass improved 2.8 kg (1.9 to 3.6; P<0.001), whereas fat mass decreased by 3.0 kg (1.1 to 4.8; P=0.003). Lung function as evaluated by peak expiratory flow increased 12% (p<0.001) - indicating improved muscle function. Adverse effects were few. Fifteen out of 39 patients had diabetes (DM; n=4) or impaired glucose tolerance (IGT; n=11) prior to GH treatment. Among the 11 patients with IGT, three reverted to normal glucose tolerance, while three progressed to overt DM at two years of GH treatment.

The known beneficial effects of GH treatment upon body composition in PWS are maintained during two years continuous treatment. With appropriate control, GH is a safe treatment option in adults with PWS.