title: Route-dependent endocrine and metabolic effects of estrogen replacement therapy.
abstract: The route of estrogen replacement therapy has a major impact on the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis. Estrogen administration by the oral, but not the transdermal, route reduces IGF-I and increases GH levels in postmenopausal women. This perturbation of the GH-IGF-I axis occurs with different forms of estrogen treatment, indicating that the dissociation of the somatotropic axis and concomitant increase in GH-binding protein levels are intrinsic effects of the oral route of estrogen administration. In clinical studies, oral estrogen reduced postprandial lipid oxidation, compared with transdermal estrogen. Oral estrogen was also associated with a reduction in lean body mass and an increase in fat mass, compared with transdermal estrogen. In contrast, the route of estrogen therapy had no impact on carbohydrate metabolism or the estrogen-induced increase in bone mineral density. The findings of route-dependent changes in body composition add a new dimension to health considerations concerning estrogen therapy in postmenopausal women and may have significant implications for estrogen replacement therapy in young hypogonadal females.
authors.affiliation: Department of Medicine, St George Hospital and University of New South Wales, Australia. A.OSullivan@unsw.edu.au
authors.forename: A J
authors.initials: AJ
authors.lastname: O'Sullivan
authors.forename: K K
authors.initials: KK
authors.lastname: Ho
mesh_terms: D000279:Administration, Cutaneous; D000284:Administration, Oral; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D015519:Bone Density; D018592:Cross-Over Studies; D004734:Energy Metabolism; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000008:administration & dosage*; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage; D005260:Female; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007700:Kinetics; D015227:Lipid Peroxidation; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage; D011446:Prospective Studies
chemical_list: D001786:Blood Glucose; D004967:Estrogens; D004966:Estrogens, Conjugated (USP); D007328:Insulin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D017258:Medroxyprogesterone Acetate