Possible hypothalamic impotence. Male counterpart to hypothalamic amenorrhea?

Twenty-one men with erectile complaints who were found to have a low level of serum testosterone without a reciprocal elevation of the serum levels of luteinizing hormone were evaluated to identify whether the defect was of hypothalamic or of pituitary origin. Patients underwent a luteinizing hormone (LH)-follicle-stimulating hormone (FSH)-releasing hormone stimulation test that showed a normal but sluggish increase in LH and FSH levels, thus ruling out a pituitary defect and suggesting a suprapituitary abnormality. This was confirmed when, in response to clomiphene, patients had a normal increase in gonadotropin and testosterone levels. Although the basal as well as clomiphene and gonadotropin releasing hormone-stimulated levels of total testosterone and gonadotropins were identical in men less than and more than fifty years old, the elevation of free testosterone levels in response to clomiphene was higher in patients younger than fifty. This suggested that although the primary abnormality found in these patients is altered secretion of gonadotropin hormone-releasing hormone from the hypothalamus, an age-related decline in the responsivity of Leydig cells to LH may make it more manifest in older patients. Elevation of testosterone levels from a subnormal to a normal range in response to clomiphene administered for seven days suggests that the defect is functional and reversible and that the drug may be useful in treatment of sexual dysfunction in this group of patients.