Response of micropenis to topical testosterone and gonadotropin.

Five patients were treated with gonadotropin and topical testosterone for micropenis associated with hypothalamic hypogonadotropic hypogonadism. All patients received 1,000 units of gonadotropin weekly for 3 weeks, with a 6-week interval followed by 10% topical testosterone cream twice daily for 3 weeks. Serum testosterone levels were measured and remained equivalent for both modes of therapy. Average penile growth response with gonadotropin was 14.3% increase in length and 5.0% increase of girth. Topical testosterone produced an average increase of 60% in penile length and 52.9% in girth. The greatest growth response occurred in prepubertal male subjects with a minimal response in postpubertal male subjects. This study suggests that 10% topical testosterone cream twice daily will produce effective penile growth. The response appears to be greater in younger children, which is consistent with previously published studies of age-related 5 reductase activity.