Increased frequency of pulsatile luteinizing hormone-releasing hormone administration selectively decreases follicle-stimulating hormone levels in men with idiopathic azoospermia.

Men with idiopathic azoo-oligospermia and selective elevations of follicle-stimulating hormone (FSH) levels have evidence for decreased luteinizing hormone-releasing hormone (LH-RH) pulse frequency. We assessed whether increasing the frequency of pulsatile LH-RH stimulation can lower FSH levels in such men. We administered 5.0 microgram of pulsatile LH-RH subcutaneously at intervals of 30, 60, and 120 minutes for 1 week to four men who had azoospermia, elevated FSH levels, and normal LH and testosterone (T) levels. The order of administration was varied among subjects. Frequent blood samples were obtained for 6 hours before LH-RH treatment and during the last 6 hours of each regimen. Before LH-RH treatment, the FSH levels (mean +/- standard error of the mean) were 359 +/- 18 ng/ml (normal range, 30 to 230 ng/ml). During LH-RH treatment, FSH levels progressively declined from 397 +/- 68 ng/ml to 237 +/- 70 ng/ml to 175 +/- 43 ng/ml as the frequency of administration increased from every 120 to 60 to 30 minutes, respectively (P less than 0.05). Unlike the FSH levels, which showed a progressive decline, LH, T, and estradiol levels showed no consistent relationship to LH-RH pulse frequency. We conclude that (1) in men with idiopathic azoospermia and elevated FSH levels, it is possible to decrease FSH levels by increasing the frequency of pulsatile LH-RH stimulation; (2) this decline does not appear to be a result of changes in steroid feedback or pituitary down-regulation; and (3) the frequency of pulsatile LH-RH stimulation can differentially modulate LH and FSH secretion by the pituitary gland.