Clinical significance of GnRH stimulation test in male infertility

Park, Kwan Hyeun; Paick, Jae Seung; Kim, Han Gwun

Abstract

GnRH stimulation test has been used to distinguish patients with hypogonadotropic hypogonadism of pituitary origin from those with hypothalamic disease. GnRH stimulation test also has been used to identify early stage of Sertoli cell insufficiency and to know the subtle abnormalities or spermatogenesis. Some investigators reported that exaggerated FSH response after GnRH stimulation means the same diagnostic meaning as basely elevated FSH level and this in turn reflects Sertoli cell insutriciency or may help to identify patients with isolated primary germ cell failure in azoospermic patients. So they suggested the possibility that GnRH stimulation test can replace testis biopsy in male infertility. To define the normal range of the gonadotropin response after GnRH stimulation and to know the indications for GnRH stimulation test if it is useful as an evaluation method for spermatogenesis, and especially to test the possibility whether GnRH stimulation test may replace testis biopsy, we performed GnRH stimulation test in 118 infertile men and 20 fertile adult male volunteers and compared the results with testicular histology. Normal basal serum levels for LH, FSH, testosterone were 1.4-18.3( mean 9.9) mIU/ml, 2.8-18.4 (mean 10.0) mIU/ml, 2.0-9.1 (mean 5.0)ng/ml respectively, and 95% confidence intervals for the peak responses to an intravenous bolus injection of 100ug GnRH were 360-1950{mean 1098)% of the basal serum LH level, and 111-318(mean 225)% of the basal FSH level in 20 rertile adult male volunteers. The results of the FSH response in GnRH stimulation test were not helpful in distinguishing patients with bad testicular histology from those with good ones in 118 infertile men. So we came to the conclusion that GnRH stimulation test can not replace testis biopsy as an evaluation method for spermatogenesis in the majority of infertile patients.