Growth hormone induced lipolysis during short- and long-term administration in adult Prader-Willi patients

Prader-Willi syndrome (PWS) is a complex genetic disease, clinically characterised by short stature, abnormal body composition, with more body fat than lean body mass, hyperphagia and obesity. Partial growth hormone (GH) deficiency is common, and GH treatment to PWS children and adults has shown beneficial effects on body composition. In this study, we have evaluated indices of GH's lipolytic effect in 6 PWS adults analysing glycerol, lactate and glucose in dialysate from microdialysis in subcutaneous abdominal adipose tissue. The patients were four men and two women, 19-37 years old; all hypogonadal. BMI was 24.2-49.1, mean 35.9 kg/m2. All had normal serum insulin levels. They received GH therapy (Genotropin® Pfizer) during 12 months and doses were individually titrated to normal serum IGF-I for age. Immediately before treatment start and at 12 months, 30-36 h after the last GH injection, sampling of dialysate was carried out at night (11 p.m. to 7 a.m.), as well as after intravenously injection of a standardised GH dose (0.8 mg). At baseline individual mean night time glycerol and lactate were similar to levels in adults without PWS (160.7-278.1 μmol/L and 0.80-3.99 mmol/L, respectively), and did not change with 12 months GH treatment. Glucose levels were normal, except in a patient with diabetes, and did not change during the study. Compared to baseline the immediate effect of GH injection resulted in a significant increase in glycerol levels after 12 months. In conclusion, night time lipolytic response in this small group of PWS adults seemed normal and did not change after 12 months GH treatment. On the other hand short-term GH induced lipolysis increased, indicating normal lipolytic response in PWS.