[Pulsatile administration of LH-RH: diagnostic and therapeutic applications]

Hypothalamic hypogonadotropic hypogonadism (HHH), a disorder occurring in both sexes, is characterized by a partial or complete inability to synthesize and/or release LH-RH from the hypothalamus which result in absence or defects of amplitude and frequency of gonadotropin secretion. Long term substitution by pulsatile exogenous LH-RH usually result in complete normalization of both pituitary and gonadic hormones. Such a treatment allows differentiation between hypothalamic and pituitary causes of hypogonadotrophic hypogonadism. Ovulation and fertility can be achieved in most of women with hypothalamic amenorrhea treated with pulsatile LH-RH using i.v. bolus doses of 25-100 ng/kg at 1-2 h intervals. In opposite LH-RH therapy yields inferior results to human menopausal gonadotropin (hMG) in chronic anovulatory patients with persistent LH secretion or polycystic ovary syndrome (PCOS) as shown by one randomized and several non-controlled studies. Successful pulsatile LH-RH treatment following a 2 months LH-RH analog suppression in PCOS previously refractory to LH-RH alone represents a new promising approach. The majority of men with complete HHH begin to produce sperm only after 1 year of therapy. Both the testicular volume and the mean sperm concentrations were below the normal values after 2 years of treatment in spite of normalization of testosterone, LH and FSH levels. Pulsatile LH-RH does not seem significantly improve the treatment of infertile HHH men compared to hMH/hCG.