Serum FSH and LH levels in men after administration of a long-acting LH-RH preparation.

The effects of the natural gonadotropin releasing hormone (LH-RH) and of a long-acting analogue, desgly10-D-leu6-LH-RH ethylamide, on the serum FSH, LH, testosterone and oestradiol-17 beta levels were studied in healthy men. The basal value for FSH was 3.58 +/- 0.47 mU/ml (SE), for LH 6.33 +/- 1.19 mU/ml. Following an intravenous dose of LH-RH the values increased by 3.40 +/- 0.88 and 25.99 +/- 5.67 mU/ml, respectively. After intravenous administration of the long-acting analogue, the peak FSH exceeded the basal value by 12.89 +/- 6.95 mU/ml, while LH increased by 41.27 +/- 4.72 mU/ml. The effect of the analogue on FSH and LH lasted 693 min and 862 min, respectively. Neither preparation changed the serum testosterone or oestradiol-17 beta levels essentially. The results suggest that the long-acting variant of LH-RH is more suitable than the natural hormone for examination of the FSH and LH reserves in men.