Effect of menopause and different combined estradiol-progestin regimens on basal and growth hormone-releasing hormone-stimulated serum growth hormone, insulin-like growth factor-1, insulin-like growth factor binding protein (IGFBP)-1, and IGFBP-3 levels.

Objective: To determine the effects of menopause and three different formulations of E2 plus medroxyprogesterone acetate on serum concentrations of basal and growth hormone-releasing hormone (GHRH)-stimulated growth hormone (GH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein (IGFBP)-1, IGFBP-3, insulin, and C peptide.

Methods: Prospective, controlled trial. Methods: Menopausal outpatient clinic at an academic tertiary care hospital. Methods: Nineteen postmenopausal women with different menopausal ages. Seventeen premenopausal women were included as controls. Methods: Oral estrogen (E2 valerate, 2 mg/d) or transdermal estrogen (50-microg or 100-microg E2 patch) was administered for 8 weeks. Medroxyprogesterone acetate (5 mg/d) was administered during weeks 3, 4, 7, and 8 of each protocol. Blood samples were collected before treatment and after the completion of each protocol from postmenopausal women, and on cycle days 6-8 from premenopausal women. Methods: Levels of GH, IGF-1, IGFBP-1, IGFBP-3, insulin, and C peptide.

Results: Basal GH levels were negatively correlated with age in premenopausal women but not in postmenopausal women. The area under the GHRH-induced GH curve decreased in older postmenopausal women after the oral estrogen protocol. Levels of IGF-1 diminished after the oral E2 protocol in postmenopausal women.

Conclusions: The administration of oral, but not transdermal, E2 plus medroxyprogesterone acetate at the usual clinical doses used in postmenopausal women decreased IGF-1 levels and the response of GH to GHRH in older women. No substantial changes were detected in IGFBP-1, IGFBP-3, insulin, or C peptide levels.