Treatment of hypogonadotropic hypogonadal male patients with the luteinizing hormone-relasing hormone (LH-RH) anolog D-Ser(TBU)6 EA10 LH-RH: transient disappearance of gonadotropin stimulation.

We have studied the effect of prolonged treatment with a long-acting luteinizing hormone-releasing hormone (LH-RH) analog (D-Ser-(TBU)6 EA10 LH-RH in six patients with isolated gonadotropin deficiency. Before treatment, all subjects responded to LH-RH (100 microgram intravenously [IV]); one responded immediately, and five after 5 daily infusions of LH-RH (200 microgram). Treatment by LH-RH analog (348 microgram every 2 days with a nasal spray for 90 or 120 days) is only efficient for 1 month; a consistent increase in serum LH and a slight increase in testosterone (T) were observed in all patients, but no increase of serum follicle-stimulating hormone (FSH) was detectable. Then a paradoxical effect appeared: LH and T levels returned to the basal values. Moreover, this treatment induced refractoriness of the pituitary to LH-RH for several months after the end of treatment. The appearance of antibodies to LH-RH and LH-RH analog was eliminated. A pituitary response was obtained in three patients when a new LH-RH stimulation was repeated 7 and 11 months after the end of treatment. The mechanism of this pituitary desensitization is discussed.