Age-related alteration of the hypothalamic-pituitary-gonadal axis in sexually impotent males

On 7 healthy normal men and 32 sexual impotent males aging between 45 and 75 years, total testosterone (T), oestradiol, luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin were measured. Additionally LH and FSH was measured after injection of 25 and 100 micrograms LHRH. The main criteria for inclusion in the study were a reduced or nonexistent capacity to have an erection during intercourse and no clinical signs of endocrine disease. The group was divided in young impotent males (group I, less than 60 years) and old impotent males (group II, at least 60 years). The healthy males served as controls (group III). None of the intergroup differences for the basal hormones were statistically significant. But 7 of the man in group I and II showed pathological low T levels (less than or equal to 300 micrograms/100 mg). The high incidence of pathological low T levels in these patients suggests that measurement of plasma T levels is recommendable in the routine diagnostic examination of all sexual impotent males. Plasma levels of LH and FSH increased significantly in all groups following injection of LHRH. At delta 25 min LH was increased significantly in group II following 100 micrograms LHRH compared to group I and III; following 25 micrograms LH and FSH was increased significantly in group II compared to group I. The present findings suggest that, while pituitary function is normal in young and old sexual impotent males, T production may be inadequate in some older patients. Since the present patients failed to show clinical signs of endocrine disease, the abnormal response to LHRH in some of the older sexual impotent males indicates that these patients had a subclinical endocrine disorder.U