THE ANTERIOR-PITUITARY RESPONSE TO A GONADOTROPIN-RELEASING-HORMONE CHALLENGE TEST IN NORMAL OLDER REPRODUCTIVE-AGE WOMEN

Objective: To assess the pituitary responsiveness to GnRH stimulation of premenopausal women relative to age. Design: Older and younger repr oductive-age women underwent the GnRH stimulation test in the early fo llicular phase of the menstrual cycle. Setting: Female subjects in an academic research environment. Patients: Women aged 21 to 44 years con sisting of normal volunteers and infertility patients. Interventions: Gonadotropin-releasing hormone was administered intravenously between days 2 and 4 of the menstrual cycle. Blood samples were collected from -20 minutes before to 120 minutes after administration. Main Outcome Measure: Luteinizing hormone, FSH, inhibin, and E(2) levels. Results: No significant difference in baseline values existed between older and younger women with regard to LH, inhibin, and E(2), but basal FSH lev els were higher in older women. A significantly diminished percent of LH and percent FSH change above baseline occurred 30 minutes after GnR H administration in the older women compared with younger women. No ch ange in inhibin or E(2) levels could be detected during the sampling p eriod. Conclusions: The present study demonstrates marked attenuation of the acute pituitary LH response (sensitivity) to GnRH stimulation i n older women when compared with a younger cohort.