Endocrine function in the Prader-Willi syndrome.

Hypothalamic, pituitary and gonadal function was studied in five male and three female patients with the Prader-Willi syndrome. All were clinically hypogonadal: all males had low circulating testosterone levels, although in two females basal plasma oestradiol was within the normal range for the early follicular phase of the menstrual cycle. Basal gonadotrophin levels were low and the response to the intravenous ater 10 days and 6 weeks treatment with oral clomiphene (200 mg daily) was followed by a normal rise in luteinizing hormone (LH) and follicle stimulating hormone (FSH) in four out of five patients tested. All five males were tested with human chorionic gonadotrophin (hCG) and the rise in plasma testosterone was subnormonal in four. Treatment with hCG was continued for 6 weeks in these four patients, but in only one did testosterone levels rise (transiently) to the normal adult male range. In one female patient studied no rise in plasma oestradiol was detected in response to human menopausal gonadotrophin (hMG). These results suggest that the hypogonadism in the Prader-Willi syndrome is due to combined hypothalamic and primary gonadal abnormalities.