Comparison of the Effects of Subcutaneous and Intravenous Injection of Synthetic LH-Releasing Hormone (LH-RH) on Serum LH and FSH Levels in Men1

Abstract

The efficacy of 100 μg of synthetic LH-RH administered subcutaneously or iv to the same subjects 3 weeks apart was compared. At the time of each injection, the mean baseline levels of both LH and FSH were unchanged. The mean maximal levels of LH and FSH after subcutaneous administration of LH-RH were similar to those observed after iv injection of the same dose, although the patterns of change differed. After the serum LH and FSH values had reached a peak, they occasionally fell for a short period of time at a rapid rate which was in some cases slower than the reported disappearance time of these hormones. This suggested a temporary cessation of secretion of LH and FSH after maximal stimulation. The results indicate that at the dose used in this study, the subcutaneous and iv routes of administration of LH-RH are equally effective in increasing serum LH and FSH concentrations.