title: Effects of the route of oestrogen administration on IGF-1 and IGFBP-3 in healthy postmenopausal women: results from a randomized placebo-controlled study.
abstract: OBJECTIVE
  Oestrogens can modulate the action or secretion of GH. Previous studies in postmenopausal women have shown a differential effect between transdermal 17beta-oestradiol and oral ethynyl-oestradiol on GH and IGF-1 concentrations. This secondary analysis, based on a large randomized trial, aimed to estimate the effect of the route of administration of 17beta-oestradiol in combined hormone replacement therapy with progesterone on IGF-1 and IGFBP-3 levels.
  
  
  METHODS
  IGF-1 and IGFBP-3 were evaluated in a randomized study of 196 healthy postmenopausal women who were randomly allocated to receive on a continuous basis either 1 mg of 17beta-oestradiol orally combined with a daily intake of 100 mg progesterone (group 1; n = 63), or 50 microg of 17beta-oestradiol transdermally combined with a daily intake of 100 mg progesterone (group 2; n = 68), or triple dummy placebo (group 3; n = 65) over a 6-month period. IGF1 and IGFBP-3 levels were available for 133 women.
  
  
  RESULTS
  Oral oestrogen significantly decreased IGF-1 levels compared to placebo (P = 0.04) and transdermal oestrogen (P = 0.004), whereas transdermal oestrogen had no effect on IGF-1 levels compared to placebo (P = 0.56). As regards IGFBP-3, no significant difference was detected between the three groups.
  
  
  CONCLUSIONS
  Our data indicate that the route of oestrogen administration can influence IGF-1 levels. IGF-1 concentrations decreased significantly with oral oestrogen, whereas no significant change was observed with transdermal oestrogen at 6 months. The clinical relevance of these differential effects remains to be determined, particularly with regard to the risk for cardiovascular diseases.
authors.affiliation: Service Endocrinologie, CHU de Brest, Hôpital Cavale Blanche, Brest, France. emmanuel.sonnet@chu-brest.fr
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Sonnet
authors.forename: Karine
authors.initials: K
authors.lastname: Lacut
authors.forename: Nathalie
authors.initials: N
authors.lastname: Roudaut
authors.forename: Dominique
authors.initials: D
authors.lastname: Mottier
authors.forename: Véronique
authors.initials: V
authors.lastname: Kerlan
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Oger
mesh_terms: D000279:Administration, Cutaneous; D000284:Administration, Oral; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015914:Estrogen Replacement Therapy / Q000379:methods*; D004967:Estrogens / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008875:Middle Aged; D017698:Postmenopause; D011374:Progesterone / Q000008:administration & dosage; D011446:Prospective Studies; D018709:Statistics, Nonparametric
chemical_list: D015415:Biomarkers; D004967:Estrogens; D018972:Insulin-Like Growth Factor Binding Protein 3; D011374:Progesterone; D007334:Insulin-Like Growth Factor I