Clinical effects of treatment for hypogonadism in male adolescents with Prader-Labhart-Willi syndrome.

BACKGROUND In boys with Prader-Labhart-Willi syndrome (PWS), hypogonadism causes pubertal arrest and reduces pubertal muscle growth. Formerly, it was assumed that therapy with gonadal hormones accentuates behaviour abnormalities in PWS. Our aim was to assess the clinical effects of human chorionic gonadotropin (hCG) therapy on pubertal development, muscle mass and behaviour in adolescents with PWS. METHODS 6 peripubertal boys with PWS undergoing long-term treatment with growth hormone were examined 6-monthly for at least 2 years before and after pubertal arrest (13.5 +/- 0.3 years, mean +/- SEM) and the beginning of hCG therapy (500-1,500 IU twice weekly, intramuscularly). Height, weight, pubertal stage, bone age, body composition (by dual-energy X-ray absorptiometry), testosterone levels and behaviour abnormalities (obtained from parents) were assessed. RESULTS Testicular volume and lean mass were reduced in pubertal boys with PWS. During hCG therapy, testosterone levels and lean mass significantly increased (at the beginning and after 2 years of hCG therapy: 2.3 +/- 0.9 and 10.7 +/- 1.3 nmol/l, -3.1 +/- 0.3 and -1.4 +/- 0.6 SD, respectively), and fat mass stabilized at 38%. The characteristically observed PWS-associated problems, mood instability, aggressiveness and difficulties in social interaction, did not deteriorate during therapy. CONCLUSION In the present study, timely application of hCG to treat hypogonadism in boys with PWS promoted virilization and normalized muscle mass without detrimental effects on behaviour. Larger studies comparing hCG therapy with testosterone replacement would be useful.