The effect of gonadotropin-releasing hormone agonists on growth hormone secretion in adult premenopausal women.

Suppression of the pituitary-gonadal axis by the administration of gonadotropin-releasing hormone agonists (GnRH-a) has been used for a variety of endocrinological and gynecological disorders. The suppressive effect of GnRH-a on luteinizing hormone, follicle-stimulating hormone, and sex steroid production is well documented. However, little is known regarding the effect of GnRH-a on other aspects of pituitary function. The purpose of the present study was to determine the effect of GnRH-a treatment on growth hormone-releasing hormone (GH-RH)-stimulated GH release in premenopausal women. Eight control women and seven women, who were receiving a GnRH-a, were recruited. Before and after a bolus infusion of human GH-RH, blood samples were obtained over 3 hours and analyzed for GH by immunoassay. Basal GH and insulin-like growth factor levels were not statistically different between the two groups. However, basal levels of estradiol and the integrated GH response after GH-RH were significantly lower in the GnRH-a treated women. The reduction in GH-RH-stimulated GH release in GnRH-a treated women may be attributed to diminished endogenous estrogen secretion, or to direct pituitary suppression by GnRH-a, or both.